我们知道CALayer不能直接响应任何响应链事件，所以不能直接处理点击事件。但是依然有两种方法可以帮助我们实现捕捉并且处理CALayer的点击事件。
运行效果:
运行效果
方法一:convertPoint:
@interface CALayerPointVC ()
@property (nonatomic, strong) CALayer *redLayer;
@property (nonatomic, strong) CALayer *yellowLayer;
@end
@implementation CALayerPointVC
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
self.redLayer = [CALayer layer];
self.redLayer.frame = CGRectMake(100, 100, 100, 100);
self.redLayer.backgroundColor = [UIColor redColor].CGColor;
[self.view.layer addSublayer:self.redLayer];
self.yellowLayer = [CALayer layer];
self.yellowLayer.frame = CGRectMake(100, 200, 100, 100);
self.yellowLayer.backgroundColor = [UIColor yellowColor].CGColor;
[self.view.layer addSublayer:self.yellowLayer];
}
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
CGPoint point = [[touches anyObject] locationInView:self.view];
CGPoint redPoint = [self.redLayer convertPoint:point fromLayer:self.view.layer];
CGPoint yellowPoint = [self.yellowLayer convertPoint:point fromLayer:self.view.layer];
if ([self.redLayer containsPoint:redPoint]) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"point red" message:@"" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[alert show];
}
if ([self.yellowLayer containsPoint:yellowPoint]) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"point yellow" message:@"" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[alert show];
}
}
首先使用locationInView方法获取到点击在view上的坐标。convertPoint：fromLayer ：方法传入一个CGPoint来转换坐标系，将在其父图层上的坐标转换为相对于图层自身的坐标，这样转换坐标系的方法还有以下几个：
- (CGPoint)convertPoint:(CGPoint)point fromLayer:(CALayer *)layer;
- (CGPoint)convertPoint:(CGPoint)point toLayer:(CALayer *)layer;
- (CGRect)convertRect:(CGRect)rect fromLayer:(CALayer *)layer;
- (CGRect)convertRect:(CGRect)rect toLayer:(CALayer *)layer;
得到触摸点相对于图层自身的坐标之后，调用containsPoint:方法。containsPoint:方法传入一个CGPoint类型参数，如果这个点在图层的frame内，则返回YES，否则返回NO。这样，就实现了对CALayer点击事件的处理。
方法二:hitTest:
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
CGPoint point = [[touches anyObject] locationInView:self.view];
CALayer *layer = [self.view.layer hitTest:point];
if (layer == self.redLayer) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"point red" message:@"" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[alert show];
}else if (layer == self.yellowLayer){
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"point yellow" message:@"" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
[alert show];
}
}
hitTest:同样传入一个CGPoint类型参数，但它的返回值不是BOOL类型，而是图层本身。如果点击的位置在最外层图层之外，则返回nil。
使用hitTest:时有一点需要注意：
hitTest:返回的顺序严格按照图层树的图层顺序。
