RxSwift官方实例七（UIPickerView）
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UIPickerView的Rx实现分析
RxPickerViewDelegateProxy分析
RxCocoa已经实现了RxPickerViewDelegateProxy，该类继承DelegateProxy基类，遵守DelegateProxyType、UIPickerViewDelegate协议：
extension UIPickerView: HasDelegate {
public typealias Delegate = UIPickerViewDelegate
}open class RxPickerViewDelegateProxy
: DelegateProxy
, DelegateProxyType
, UIPickerViewDelegate {/// Typed parent object.
public weak private(set) var pickerView: UIPickerView?/// - parameter pickerView: Parent object for delegate proxy.
public init(pickerView: ParentObject) {
self.pickerView = pickerView
super.init(parentObject: pickerView, delegateProxy: RxPickerViewDelegateProxy.self)
}// Register known implementationss
public static func registerKnownImplementations() {
self.register { RxPickerViewDelegateProxy(pickerView: $0) }
}
}
UIPickerViewDelegate协议的所有函数在这个类中都没有实现，最终会进行消息转发。RxPickerViewDataSourceProxy分析
RxCocoa已经实现了RxPickerViewDataSourceProxy，该类继承DelegateProxy基类，遵守DelegateProxyType、UIPickerViewDataSource协议：extension UIPickerView: HasDataSource {
public typealias DataSource = UIPickerViewDataSource
}private let pickerViewDataSourceNotSet = PickerViewDataSourceNotSet()final private class PickerViewDataSourceNotSet: NSObject, UIPickerViewDataSource {
func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 0
}func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return 0
}
}/// For more information take a look at `DelegateProxyType`.
public class RxPickerViewDataSourceProxy
: DelegateProxy
, DelegateProxyType
, UIPickerViewDataSource {/// Typed parent object.
public weak private(set) var pickerView: UIPickerView?/// - parameter pickerView: Parent object for delegate proxy.
public init(pickerView: ParentObject) {
self.pickerView = pickerView
super.init(parentObject: pickerView, delegateProxy: RxPickerViewDataSourceProxy.self)
}// Register known implementations
public static func registerKnownImplementations() {
self.register { RxPickerViewDataSourceProxy(pickerView: $0) }
}private weak var _requiredMethodsDataSource: UIPickerViewDataSource? = pickerViewDataSourceNotSet// MARK: UIPickerViewDataSource/// Required delegate method implementation.
public func numberOfComponents(in pickerView: UIPickerView) -> Int {
return (_requiredMethodsDataSource ?? pickerViewDataSourceNotSet).numberOfComponents(in: pickerView)
}/// Required delegate method implementation.
public func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return (_requiredMethodsDataSource ?? pickerViewDataSourceNotSet).pickerView(pickerView, numberOfRowsInComponent: component)
}/// For more information take a look at `DelegateProxyType`.
public override func setForwardToDelegate(_ forwardToDelegate: UIPickerViewDataSource?, retainDelegate: Bool) {
_requiredMethodsDataSource = forwardToDelegate ?? pickerViewDataSourceNotSet
super.setForwardToDelegate(forwardToDelegate, retainDelegate: retainDelegate)
}
}
扩展UIPickerView遵守HasDataSource协议，使
RxPickerViewDataSourceProxy满足条件进而实现了DelegateProxyType协议中定义的如下两个函数：extension DelegateProxyType where ParentObject: HasDataSource, Self.Delegate == ParentObject.DataSource {
public static func currentDelegate(for object: ParentObject) -> Delegate? {
return object.dataSource
}public static func setCurrentDelegate(_ delegate: Delegate?, to object: ParentObject) {
object.dataSource = delegate
}
}
定义
PickerViewDataSourceNotSet这个类为UIPickerViewDataSource协议提供默认数据重写
setForwardToDelegate函数，将参数forwardToDelegate存储在私有属性_requiredMethodsDataSource中。UIPickerViewDataSource协议中的两个函数在这个类中实现，调用属性_requiredMethodsDataSource的方法返回结果。RxPickerViewAdapter分析
RxPickerViewAdapter是用来处理UIPickerViewDataSource、UIPickerViewDelegate协议中定义的带有返回值的函数的。RxCocoa实现了3种RxPickerViewAdapter，分别是RxStringPickerViewAdapter、RxAttributedStringPickerViewAdapter、RxPickerViewAdapter。RxPickerViewArrayDataSource分析
RxPickerViewArrayDataSource是RxStringPickerViewAdapter、RxAttributedStringPickerViewAdapter、RxPickerViewAdapter的根类，遵守UIPickerViewDataSource、SectionedViewDataSourceType协议，还定义一个泛型class RxPickerViewArrayDataSource: NSObject, UIPickerViewDataSource, SectionedViewDataSourceType {
fileprivate var items: [T] = []func model(at indexPath: IndexPath) throws -> Any {
guard items.indices ~= indexPath.row else {
throw RxCocoaError.itemsNotYetBound(object: self)
}
return items[indexPath.row]
}func numberOfComponents(in pickerView: UIPickerView) -> Int {
return 1
}func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return items.count
}
}
-
items数组属性存储所需数据，问题是他只能存一组数据。 - 实现
UIPickerViewDataSource协议。
RxPickerViewSequenceDataSource这个类继承自RxPickerViewArrayDataSource，是RxStringPickerViewAdapter、RxAttributedStringPickerViewAdapter、RxPickerViewAdapter的父类，遵守RxPickerViewArrayDataSource,
RxPickerViewDataSourceType协议，定义一个遵守Swift.Sequence协议的泛型class RxPickerViewSequenceDataSource
: RxPickerViewArrayDataSource
, RxPickerViewDataSourceType {
typealias Element = Sequencefunc pickerView(_ pickerView: UIPickerView, observedEvent: Event) {
Binder(self) { dataSource, items in
dataSource.items = items
pickerView.reloadAllComponents()
}
.on(observedEvent.map(Array.init))
}
}
func pickerView(_ pickerView: UIPickerView, observedEvent: Event)函数的实现：- 构建一个
Binder并执行on操作，实际相当于直接执行构建Binder的binding闭包。 - 将
Event类型参数observedEvent转化为Event作为on操作的参数。 - 在构建
Binder的binding闭包中，将数组赋值给items属性并刷新整个UIPickerView。
RxStringPickerViewAdapter是不可被继承的，自身继承自RxPickerViewSequenceDataSource并且遵守UIPickerViewDelegate协议：final class RxStringPickerViewAdapter
: RxPickerViewSequenceDataSource
, UIPickerViewDelegate {typealias TitleForRow = (Int, Sequence.Element) -> String?
private let titleForRow: TitleForRowinit(titleForRow: @escaping TitleForRow) {
self.titleForRow = titleForRow
super.init()
}func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return titleForRow(row, items[row])
}
}
属性
titleForRow存储将items数组中的元素转化为String类型的闭包。- (nullable NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component函数中执行titleForRow闭包并返回其结果。RxAttributedStringPickerViewAdapter、RxPickerViewAdapter的实现与RxStringPickerViewAdapter类似，不同的是分别存储attributedTitleForRow（将数组中元素转化为NSAttributedString富文本）、viewForRow（将数组中元素转化为UIView视图）的闭包，实现不同的UIPickerViewDelegate协议函数返回执行闭包的返回值：final class RxAttributedStringPickerViewAdapter: RxPickerViewSequenceDataSource, UIPickerViewDelegate {
typealias AttributedTitleForRow = (Int, Sequence.Element) -> NSAttributedString?
private let attributedTitleForRow: AttributedTitleForRowinit(attributedTitleForRow: @escaping AttributedTitleForRow) {
self.attributedTitleForRow = attributedTitleForRow
super.init()
}func pickerView(_ pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? {
return attributedTitleForRow(row, items[row])
}
}final class RxPickerViewAdapter: RxPickerViewSequenceDataSource, UIPickerViewDelegate {
typealias ViewForRow = (Int, Sequence.Element, UIView?) -> UIView
private let viewForRow: ViewForRowinit(viewForRow: @escaping ViewForRow) {
self.viewForRow = viewForRow
super.init()
}func pickerView(_ pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusing view: UIView?) -> UIView {
return viewForRow(row, items[row], view)
}
}
基于UIPickerView的Reactive扩展分析
定义delegate、dataSource两个函数用于获取Rx代理对象，方便使用：
public var delegate: DelegateProxy {
return RxPickerViewDelegateProxy.proxy(for: base)
}
public var dataSource: DelegateProxy {
return RxPickerViewDataSourceProxy.proxy(for: base)
}
定义setDelegate函数通过
installForwardDelegate函数为Rx代理对象设置forwardDelegate并返回一个置空forwardDelegate的Disposables：public func setDelegate(_ delegate: UIPickerViewDelegate)
-> Disposable {
return RxPickerViewDelegateProxy.installForwardDelegate(delegate, retainDelegate: false, onProxyForObject: self.base)
}
public func items(adapter: Adapter) -> (_ source: Source) -> Disposable where Source.Element == Adapter.Element函数，这个函数很重要，数据的绑定最终都会走到这个函数：public func items(adapter: Adapter)
-> (_ source: Source)
-> Disposable where Source.Element == Adapter.Element {
return { source in
let delegateSubscription = self.setDelegate(adapter)
let dataSourceSubscription = source.subscribeProxyDataSource(ofObject: self.base, dataSource: adapter, retainDataSource: true, binding: { [weak pickerView = self.base] (_: RxPickerViewDataSourceProxy, event) in
guard let pickerView = pickerView else { return }
adapter.pickerView(pickerView, observedEvent: event)
})
return Disposables.create(delegateSubscription, dataSourceSubscription)
}
}
- 此函数接收一个遵守
RxPickerViewDataSourceType、UIPickerViewDataSource、UIPickerViewDelegate这三个协议的参数adapter，返回一个(_ source: Source) -> Disposable绑定数据的闭包 - 构建返回闭包，将原函数参数
adapter通过setDelegate函数设置给RxDelegate代理对象的forwardDelegate。 - 将原函数参数
adapter通过原函数参数source的subscribeProxyDataSource（见下方分析）函数设置给RxDataSource代理对象的forwardDelegate，并在binding参数的闭包中执行adapter的func pickerView(_ pickerView: UIPickerView, observedEvent: Event函数绑定数据。) - 最后将
setDelegate和subscribeProxyDataSource函数返回的Disposables组合成一个Disposables返回。
itemTitles，itemAttributedTitles，items这三个函数分别是将一个Observable中的数据绑定到UIPickerView的标题、富文本标题、以及view上：public func itemTitles
(_ source: Source)
-> (_ titleForRow: @escaping (Int, Sequence.Element) -> String?)
-> Disposable where Source.Element == Sequence {
return { titleForRow in
let adapter = RxStringPickerViewAdapter(titleForRow: titleForRow)
return self.items(adapter: adapter)(source)
}
}
public func itemAttributedTitles
(_ source: Source)
-> (_ attributedTitleForRow: @escaping (Int, Sequence.Element) -> NSAttributedString?)
-> Disposable where Source.Element == Sequence {
return { attributedTitleForRow in
let adapter = RxAttributedStringPickerViewAdapter(attributedTitleForRow: attributedTitleForRow)
return self.items(adapter: adapter)(source)
}
}
public func items
(_ source: Source)
-> (_ viewForRow: @escaping (Int, Sequence.Element, UIView?) -> UIView)
-> Disposable where Source.Element == Sequence {
return { viewForRow in
let adapter = RxPickerViewAdapter(viewForRow: viewForRow)
return self.items(adapter: adapter)(source)
}
}
- 这三个函数的形式都是一样的，接收一个
Observable序列的数据参数，返回一个闭包。 - 不同的是返回的闭包的参数不一样，分别是将原函数
Observable序列的元素转化为String、NSAttributedString、UIView的闭包。 - 原函数都是直接构建一个闭包返回，在闭包中将转换原函数
Observable序列的元素的闭包参数分别构建为RxStringPickerViewAdapter、RxAttributedStringPickerViewAdapter、RxPickerViewAdapter对象，然后调用前面分析的public func items(adapter: Adapter) -> (_ source: Source) -> Disposable where Source.Element == Adapter.Element函数通过各自的adapter将将原函数Observable序列的元素绑定到UIPickerView并返回Disposable。
public func model(at indexPath: IndexPath) throws -> T 函数用于获取每个单元格中的数据对象：public func model(at indexPath: IndexPath) throws -> T {
let dataSource: SectionedViewDataSourceType = castOrFatalError(self.dataSource.forwardToDelegate(), message: "This method only works in case one of the `rx.itemTitles, rx.itemAttributedTitles, items(_ source: O)` methods was used.")return castOrFatalError(try dataSource.model(at: indexPath))
}
- 取出
self.dataSource.forwardToDelegate()对象，实际上就是前面设置的adapter对象。 - 由于
adapter对象的基类RxPickerViewArrayDataSource实现了SectionedViewDataSourceType协议中定义的func model(at indexPath: IndexPath) throws -> Any函数，所以返回其调用结果。
itemSelected序列，并使用map操作符更改序列元素。modelSelected序列是通过itemSelected序列进行转化而来：public var itemSelected: ControlEvent<(row: Int, component: Int)> {
let source = delegate
.methodInvoked(#selector(UIPickerViewDelegate.pickerView(_:didSelectRow:inComponent:)))
.map {
return (row: try castOrThrow(Int.self, $0[1]), component: try castOrThrow(Int.self, $0[2]))
}
return ControlEvent(events: source)
}
public func modelSelected(_ modelType: T.Type) -> ControlEvent {
let source = itemSelected.flatMap { [weak view = self.base as UIPickerView] _, component -> Observable in
guard let view = view else {
return Observable.empty()
}let model: [T] = try (0 ..< view.numberOfComponents).map { component in
let row = view.selectedRow(inComponent: component)
return try view.rx.model(at: IndexPath(row: row, section: component))
}return Observable.just(model)
}return ControlEvent(events: source)
}
ObservableType扩展分析
func subscribeProxyDataSource(ofObject object: DelegateProxy.ParentObject, dataSource: DelegateProxy.Delegate, retainDataSource: Bool, binding: @escaping (DelegateProxy, Event) -> Void) -> Disposable 函数的作用是为Rx代理对象设置forwardDelegate对象和订阅自身时执行binding参数中的闭包相关操作：extension ObservableType {
func subscribeProxyDataSource(ofObject object: DelegateProxy.ParentObject, dataSource: DelegateProxy.Delegate, retainDataSource: Bool, binding: @escaping (DelegateProxy, Event) -> Void)
-> Disposable
where DelegateProxy.ParentObject: UIView
, DelegateProxy.Delegate: AnyObject {
let proxy = DelegateProxy.proxy(for: object)
let unregisterDelegate = DelegateProxy.installForwardDelegate(dataSource, retainDelegate: retainDataSource, onProxyForObject: object)
// this is needed to flush any delayed old state (https://github.com/RxSwiftCommunity/RxDataSources/pull/75)
object.layoutIfNeeded()let subscription = self.asObservable()
.observeOn(MainScheduler())
.catchError { error in
bindingError(error)
return Observable.empty()
}
// source can never end, otherwise it would release the subscriber, and deallocate the data source
.concat(Observable.never())
.takeUntil(object.rx.deallocated)
.subscribe { [weak object] (event: Event) inif let object = object {
assert(proxy === DelegateProxy.currentDelegate(for: object), "Proxy changed from the time it was first set.\nOriginal: \(proxy)\nExisting: \(String(describing: DelegateProxy.currentDelegate(for: object)))")
}binding(proxy, event)switch event {
case .error(let error):
bindingError(error)
unregisterDelegate.dispose()
case .completed:
unregisterDelegate.dispose()
default:
break
}
}return Disposables.create { [weak object] in
subscription.dispose()
object?.layoutIfNeeded()
unregisterDelegate.dispose()
}
}
}
- 这个函数接收三个参数分别是Rx代理对象的持有者
object、Rx代理类关联类型Delegate的dataSource、是否持有dataSource的retainDataSource、数据绑定闭包binding。 - 首先调用Rx代理类的
proxy函数获得Rx代理对象，接着调用installForwardDelegate函数设置Rx代理对象的forwardDelegate。 - 然后本
Observable序列执行subscribe操作进行订阅并在其参数on闭包中执行binding闭包。 - 最后将自身订阅和
installForwardDelegate函数放回的Disposable组合成一个返回。
构建3个UIPickerView分别为pickerView1、pickerView2、pickerView3……
然后构建数据并分别绑定到上面的3个UIPickerView：
// 绑定pickerView1
Observable.just([1, 2, 3, 4, 5, 6, 7, 8, 9])
.bind(to: pickerView1.rx.itemTitles, curriedArgument: { "\($1)" })
.disposed(by: bag)
pickerView1.rx.itemSelected
.subscribe(onNext: { print("选中了第\($1)列第\($0)行") })
.disposed(by: bag)
pickerView1.rx.modelSelected(Int.self)
.subscribe(onNext: { print("选中了元素\($0.first ?? 0)") })
.disposed(by: bag)// 绑定pickerView2
Observable.just([1, 2, 3, 4, 5, 6, 7, 8, 9])
.bind(to: pickerView2.rx.itemAttributedTitles, curriedArgument: { NSAttributedString(string: "\($1)", attributes: [NSAttributedString.Key.foregroundColor: UIColor.random]) })
.disposed(by: bag)pickerView2.rx.itemSelected
.subscribe(onNext: { print("选中了第\($1)列第\($0)行") })
.disposed(by: bag)pickerView2.rx.modelSelected(Int.self)
.subscribe(onNext: { print("选中了元素\($0.first ?? 0)") })
.disposed(by: bag)// 绑定pickerView3
Observable.just(Array(0..<10).map({ (_) -> UIColor in UIColor.random }))
.bind(to: pickerView3.rx.items, curriedArgument: { _, color, _ in
let view = UIView()
view.backgroundColor = color
return view
}).disposed(by: bag)
pickerView3.rx.itemSelected
.subscribe(onNext: { print("选中了第\($1)列第\($0)行") })
.disposed(by: bag)
pickerView3.rx.modelSelected(UIColor.self)
.subscribe(onNext: { print("选中了元素\($0.first ?? UIColor.white)") })
.disposed(by: bag)
数据绑定过程分析
Observable.just([1, 2, 3, 4, 5, 6, 7, 8, 9])
.bind(to: pickerView1.rx.itemTitles, curriedArgument: { "\($1)" })
.disposed(by: bag)
RxCocoa对
func bind(to binder: (Self) -> (R1) -> R2, curriedArgument: R1) -> R2 函数的实现：public func bind(to binder: (Self) -> (R1) -> R2, curriedArgument: R1) -> R2 {
return binder(self)(curriedArgument)
}
泛型
R1为(Int, Sequence.Element) -> String?类型闭包，泛型R2为Disposable类型。于是上面数据绑定的代码等价于：pickerView1.rx
.itemTitles(Observable.just([1, 2, 3, 4, 5, 6, 7, 8, 9]))({ "\($1)" })
.disposed(by: bag)
数据绑定的完整过程：
- 构建元素是一个
[int]类型的原数据Observable序列。 - 把原数据
Observable序列作为参数执行pickerView1.rx.itemTitles函数，返回一个(titleForRow: (Int, Sequence.Element) -> String?) -> Disposable类型的闭包。 - 将类型为
(Int, Sequence.Element) -> String?的参数curriedArgument这个闭包再作为titleForRow参数执行上面的(titleForRow: (Int, Sequence.Element) -> String?) -> Disposable闭包。 -
(titleForRow: (Int, Sequence.Element) -> String?) -> Disposable闭包内部使用titleForRow闭包构建RxStringPickerViewAdapter类型对象adapter。 - 然后用
adapter作为参数执行func items(adapter: Adapter) -> (source: Source) -> Disposable函数返回类型为(source: Source) -> Disposable的闭包。 - 将原数据
Observable序列作为参数执行(source: Source) -> Disposable闭包。 - 闭包
(source: Source) -> Disposable内部执行setDelegate函数设置RxPickerViewDelegateProxy类型的forwardDelegate属性。 - 闭包
(source: Source) -> Disposable内部执行subscribeProxyDataSource函数设置RxPickerViewDataSourceProxy类型的forwardDelegate属性。 -
subscribeProxyDataSource函数内部订阅原数据Observable序列将[int]类型的元素作为参数执行adapter对象的func pickerView(pickerView: UIPickerView, observedEvent: Event函数。) - 最后
func pickerView(pickerView: UIPickerView, observedEvent: Event函数中将) [int]类型的元素保存到adapter对象的items属性中并执行reloadAllComponents刷新UIPickerView。 -
UIPickerView在刷新时会调用其代理对象（RxPickerViewDelegateProxy、RxPickerViewDataSourceProxy）的函数，然后在实现的协议函数中执行其forwardDelegate属性相应的函数返回数据或者通过消息转发的方式执行forwardDelegate中的函数。
pickerView1.rx.itemSelected
.subscribe(onNext: { print("选中了第\($1)列第\($0)行") })
.disposed(by: bag)
pickerView1.rx.modelSelected(Int.self)
.subscribe(onNext: { print("选中了元素\($0.first ?? 0)") })
.disposed(by: bag)
-
itemSelected通过消息转发实现。 -
modelSelected将itemSelected通过flatMap操作符转化Observable序列的行列号元素为实际数据。
pickerView1、pickerView2、pickerView3的数据绑定过程是一样的。区别无非是将数据分别绑定到单元格的title、attributedTitle、view。自定义绑定
从对
RxPickerViewArrayDataSource的分析可以看出RxCocoa只实现了将单组数据绑定到UIPickerView单元格的title、attributedTitle、view。这往往满足不了日常的开发需要，所以自定义绑定显得很重要。
实现多组数据绑定 参照
RxCocoa实现的RxStringPickerViewAdapter、RxAttributedStringPickerViewAdapter、RxPickerViewAdapter实现一个支持多组数据的基类BaseSectionedPickerViewAdapter：class BaseSectionedPickerViewAdapter: NSObject, UIPickerViewDataSource, UIPickerViewDelegate, RxPickerViewDataSourceType, SectionedViewDataSourceType {
typealias Element = [[CustomStringConvertible]]
fileprivate var items: Element = []func model(at indexPath: IndexPath) throws -> Any {
items[indexPath.section][indexPath.row]
}func numberOfComponents(in pickerView: UIPickerView) -> Int {
items.count
}
func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
items[component].count
}func pickerView(_ pickerView: UIPickerView, observedEvent: Event) {
Binder(self) { (adapter, items) in
adapter.items = items
pickerView.reloadAllComponents()
}.on(observedEvent)
}
}
实现一个简单的
SimpleSectionedPickerViewAdapter，实现func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String?函数将数据的description属性简单地绑定到title上：class SimpleSectionedPickerViewAdapter: BaseSectionedPickerViewAdapter {
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
return items[component][row].description
}
}
在页面上搭建一个
UIPickerView命名为pickerView，然后进行数据绑定：Observable.just([Array(0..<10), Array(10..<20), Array(20..<30)])
.bind(to: pickerView.rx.items(adapter: SimpleSectionedPickerViewAdapter()))
.disposed(by: bag)
RxCocoa对func bind(to binder: (Self) -> Result) -> Result 函数的实现：public func bind(to binder: (Self) -> Result) -> Result {
return binder(self)
}
泛型
Result为Disposable类型。于是上面数据绑定的代码等价于：pickerView.rx
.items(adapter: SimpleSectionedPickerViewAdapter())(Observable.just([Array(0..<10), Array(10..<20), Array(20..<30)]))
.disposed(by: bag)
数据绑定的完整过程：
- 首先构建一个
Observable序列的原数据Observable.just([Array(0..<10), Array(10..<20), Array(20..<30)]) - 构建一个
PickerViewViewAdapter类型对象作为参数执行func items(adapter: Adapter) -> (_ source: Source) -> Disposable函数返回类型为(source: Source) -> Disposable的闭包。 - 将原数据
Observable序列作为参数执行(source: Source) -> Disposable闭包。 - 接下来的过程与上面的简单绑定过程完全一致。
UIPickerView单元格的宽、高、标题、视图等内容，接下来实现更全面的数据绑定。实现完整的数据绑定 实现一个
SectionedPickerViewAdapter，与Rxcocoa实现的RxPickerViewAdapter类似：class
: BaseSectionedPickerViewAdapter, UIPickerViewDelegate {
private var viewForRow: ((UIPickerView, Int, Int, UIView?) -> UIView)?
private var titleForRow: ((UIPickerView, Int, Int) -> String)?
private var attributedTitleForRow: ((UIPickerView, Int, Int) -> NSAttributedString)?
private var widthForComponent: ((UIPickerView, Int) -> CGFloat)?
private var heightForComponent: ((UIPickerView, Int) -> CGFloat)?func pickerView(_ pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusing view: UIView?) -> UIView {
if let aView = viewForRow {
return aView(pickerView, row, component, view)
} else {
let label = UILabel()
label.textAlignment = .center
label.font = UIFont.systemFont(ofSize: 21.0)
if let aAttributedTitle = attributedTitleForRow {
label.attributedText = aAttributedTitle(pickerView, row, component)
}
else if let aTitle = titleForRow {
label.text = aTitle(pickerView, row, component)
}
else {
label.text = items[component][row].description
}return label
}
}func pickerView(_ pickerView: UIPickerView, widthForComponent component: Int) -> CGFloat {
if let width = widthForComponent {
return width(pickerView, component)
}return floor(UIScreen.main.bounds.width/CGFloat(items.count))
}func pickerView(_ pickerView: UIPickerView, rowHeightForComponent component: Int) -> CGFloat {
if let aHeight = heightForComponent {
return aHeight(pickerView, component)
}return 34.0
}init(viewForRow: ((UIPickerView, Int, Int, UIView?) -> UIView)?, widthForComponent: ((UIPickerView, Int) -> CGFloat)? = nil, heightForComponent: ((UIPickerView, Int) -> CGFloat)? = nil, titleForRow: ((UIPickerView, Int, Int) -> String)? = nil, attributedTitleForRow: ((UIPickerView, Int, Int) -> NSAttributedString)? = nil) {
super.init()
self.viewForRow = viewForRow
self.widthForComponent = widthForComponent
self.heightForComponent = heightForComponent
}
}
扩展
Base类型为UIPickerView的Reactive实现一个sectionedItems函数，与RxCocoa的func items(_ source: Source) -> (_ viewForRow: @escaping (Int, Sequence.Element, UIView?) -> UIView) -> Disposable函数类似：extension Reactive where Base: UIPickerView {
func sectionedItems
(_ source: Observable)
-> ((viewForRow: (UIPickerView, Int, Int, UIView?) -> UIView, widthForComponent: ((UIPickerView, Int) -> CGFloat)?, heightForComponent: ((UIPickerView, Int) -> CGFloat)?, titleForRow:((UIPickerView, Int, Int) -> String)?, attributedTitleForRow: ((UIPickerView, Int, Int) -> NSAttributedString)?))
-> Disposable {
return { arg in
let adapter = SectionedPickerViewAdapter(viewForRow: arg.0, widthForComponent: arg.1, heightForComponent: arg.2, titleForRow: arg.3, attributedTitleForRow: arg.4)
return items(adapter: adapter)(source)
}
}
}
最后进行数据绑定，其绑定过程与前边分析基本一致：
Observable.just([Array(0..<10), Array(10..<100), Array(100..<1000)])
.bind(to: centerPickerView.rx.sectionedItems, curriedArgument: ({ (_, row, component, _) in
let label = UILabel()
label.font = UIFont.systemFont(ofSize: 12.0)
label.textAlignment = .center
label.backgroundColor = UIColor.random
label.text = data[component][row].description
return label
}, { _, component in
switch component {
case 0:
return 40.0
case 1:
return 80.0
default:
return 120.0
}
}, { (_, _) in 50.0 }, nil, nil))
.disposed(by: bag)
【RxSwift官方实例七（UIPickerView）】通过前面对RxCocoa实现UIPickerView绑定的分析，也可以通过如下方式绑定数据：
let adapter = SectionedPickerViewAdapter(viewForRow: { (_, row, component, _) -> UIView in
let label = UILabel()
label.font = UIFont.systemFont(ofSize: 12.0)
label.textAlignment = .center
label.backgroundColor = UIColor.random
label.text = data[component][row].description
return label
}, widthForComponent: { _, component in
switch component {
case 0:
return 120.0
case 1:
return 80.0
default:
return 40.0
}
}, heightForComponent: { (_, _) in 40.0 })
Observable.just([Array(0..<10), Array(10..<100), Array(100..<1000)])
.bind(to: bottomPickerView.rx.items(adapter: adapter))
.disposed(by: bag)
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