新建两个View,一个View背景色是白色，带有圆角，一个View背景色是红色，中心点在白色View的左上角上，这样会形成什么样的效果？红色View会盖住一部分白色View如果此时把白色View的masksToBounds设置为YES,会如何？

@interface ViewController ()@property (nonatomic, weak) IBOutlet UIView *layerView1; @property (nonatomic, weak) IBOutlet UIView *layerView2; @end@implementation ViewController- (void)viewDidLoad { [super viewDidLoad]; //enable layer shadows self.layerView1.layer.shadowOpacity = 0.5f; self.layerView2.layer.shadowOpacity = 0.5f; //create a square shadow CGMutablePathRef squarePath = CGPathCreateMutable(); CGPathAddRect(squarePath, NULL, self.layerView1.bounds); self.layerView1.layer.shadowPath = squarePath; CGPathRelease(squarePath); ?//create a circular shadow CGMutablePathRef circlePath = CGPathCreateMutable(); CGPathAddEllipseInRect(circlePath, NULL, self.layerView2.bounds); self.layerView2.layer.shadowPath = circlePath; CGPathRelease(circlePath); } @end

@interface ViewController ()@property (nonatomic, weak) IBOutlet UIImageView *imageView; @end@implementation ViewController- (void)viewDidLoad { [super viewDidLoad]; //create mask layer CALayer *maskLayer = [CALayer layer]; maskLayer.frame = self.layerView.bounds; UIImage *maskImage = [UIImage imageNamed:@"Cone.png"]; maskLayer.contents = (__bridge id)maskImage.CGImage; //apply mask to image layer? self.imageView.layer.mask = maskLayer; } @end

kCAFilterLinear kCAFilterNearest kCAFilterTrilinear

@interface ViewController ()@property (nonatomic, strong) IBOutletCollection(UIView) NSArray *digitViews; @property (nonatomic, weak) NSTimer *timer; ?? @end@implementation ViewController- (void)viewDidLoad { [super viewDidLoad]; //get spritesheet image UIImage *digits = [UIImage imageNamed:@"Digits.png"]; //set up digit views for (UIView *view in self.digitViews) { //set contents view.layer.contents = (__bridge id)digits.CGImage; view.layer.contentsRect = CGRectMake(0, 0, 0.1, 1.0); view.layer.contentsGravity = kCAGravityResizeAspect; }//start timer self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(tick) userInfo:nil repeats:YES]; //set initial clock time [self tick]; }- (void)setDigit:(NSInteger)digit forView:(UIView *)view { //adjust contentsRect to select correct digit view.layer.contentsRect = CGRectMake(digit * 0.1, 0, 0.1, 1.0); }- (void)tick { //convert time to hours, minutes and seconds NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier: NSGregorianCalendar]; NSUInteger units = NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit; ? NSDateComponents *components = [calendar components:units fromDate:[NSDate date]]; //set hours [self setDigit:components.hour / 10 forView:self.digitViews[0]]; [self setDigit:components.hour % 10 forView:self.digitViews[1]]; //set minutes [self setDigit:components.minute / 10 forView:self.digitViews[2]]; [self setDigit:components.minute % 10 forView:self.digitViews[3]]; //set seconds [self setDigit:components.second / 10 forView:self.digitViews[4]]; [self setDigit:components.second % 10 forView:self.digitViews[5]]; } @end

@interface ViewController () @property (nonatomic, weak) IBOutlet UIView *containerView; @end@implementation ViewController- (UIButton *)customButton { //create button CGRect frame = CGRectMake(0, 0, 150, 50); UIButton *button = [[UIButton alloc] initWithFrame:frame]; button.backgroundColor = [UIColor whiteColor]; button.layer.cornerRadius = 10; //add label frame = CGRectMake(20, 10, 110, 30); UILabel *label = [[UILabel alloc] initWithFrame:frame]; label.text = @"Hello World"; label.textAlignment = NSTextAlignmentCenter; [button addSubview:label]; return button; }- (void)viewDidLoad { [super viewDidLoad]; //create opaque button UIButton *button1 = [self customButton]; button1.center = CGPointMake(50, 150); [self.containerView addSubview:button1]; //create translucent button UIButton *button2 = [self customButton]; ? button2.center = CGPointMake(250, 150); button2.alpha = 0.5; [self.containerView addSubview:button2]; //enable rasterization for the translucent button button2.layer.shouldRasterize = YES; button2.layer.rasterizationScale = [UIScreen mainScreen].scale; } @end