一. 创建图层继承于CALayer，并在子类实现drawInContext方法
@interface CTLayer : CALayer @end @implementation CTLayer -(void)drawInContext:(CGContextRef)ctx{
//画一个圆 CGContextSetRGBFillColor(ctx, 0, 0, 1, 1); CGContextAddEllipseInRect(ctx, CGRectMake(100, 100, 100, 100)); CGContextFillPath(ctx); } @end
在viewcontroller加载视图时，
CTLayer *layer = [CTLayer layer]; layer.bounds = CGRectMake(0, 0, 300, 300); layer.anchorPoint = CGPointMake(0,0); [layer setNeedsDisplay];//显示图层 [self.view.layer addSublayer:layer];
二. 使用代理方式创建
CTLayer *layer = [CTLayer layer]; layer.bounds = CGRectMake(0, 0, 300, 300); layer.anchorPoint = CGPointMake(0,0); layer.delegate = self; //指定代理，该代理可为任意类型 [layer setNeedsDisplay];//显示layer [self.view.layer addSublayer:layer];
实现代理方法
#pragma mark 代理方法 -(void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx{ CGContextSetRGBFillColor(ctx, 0, 0, 1, 1); CGContextAddEllipseInRect(ctx, CGRectMake(100, 100, 100, 100)); CGContextFillPath(ctx); }