CALayer绘制图层

导入

#import <QuartzCore/QuartzCore.h>

  //实例化子图层

    CALayer *myLayer = [CALayerlayer];

    

    [myLayer setBounds:CGRectMake(0,0, 200,200)];

    [myLayer setBackgroundColor:[UIColorredColor].CGColor];

    [myLayer setPosition:CGPointMake(100,100)];

    

    [self.view.layeraddSublayer:myLayer];

    

    // 提示：不能将视图设置为layer的代理

//    [myLayer setDelegate:self.view];

    [myLayer setDelegate:self];

    

    // 提示，如果要重绘CALayer，必须要调用setNeedDisplay方法

    [myLayer setNeedsDisplay];

    

    NSLog(@"%@", myLayer);

- (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx

{

    CGRect rect =CGRectMake(50,50, 100,100);

    

    CGContextSetRGBFillColor(ctx,0.0, 0.0, 1.0,1.0);

    CGContextSetRGBStrokeColor(ctx,0.0, 1.0, 0.0,1.0);

    

    CGContextAddRect(ctx, rect);

    

    CGContextDrawPath(ctx,kCGPathFillStroke);