iOS使用mask切割不规则图案

起点，终点要闭合：

CGPathAddQuadCurveToPoint(path, NULL, viewSize.width * 0.5, viewSize.height, viewSize.width, viewSize.height * 0.9); 这个方法画弧线

/**
 根据几何知识规则 生成不规则图形
 */
-(void)makeContents3{
    //生成path
    CGMutablePathRef path =CGPathCreateMutable();
    
    CGSize viewSize = self.bounds.size;
    
    CGPathMoveToPoint(path, NULL, 0, viewSize.height * 0.9);//左边直线下点
    
    CGPathAddQuadCurveToPoint(path, NULL, viewSize.width * 0.5, viewSize.height, viewSize.width, viewSize.height * 0.9);
    CGPathAddLineToPoint(path, NULL, viewSize.width, 0);
    CGPathAddLineToPoint(path, NULL, 0, 0);
    CGPathAddLineToPoint(path, NULL, 0, viewSize.height * 0.9); // 形成闭环
    
    
    CAShapeLayer *maskLayer= [CAShapeLayer layer];
    
    //        maskLayer.path=[UIBezierPath bezierPathWithRoundedRect:self.indicateView.bounds cornerRadius:30].CGPath;
    
    maskLayer.path=path;
    
    maskLayer.fillColor=[UIColor blackColor].CGColor;//填充色
    maskLayer.strokeColor=[UIColor redColor].CGColor;
    maskLayer.frame=self.bounds;
    maskLayer.contentsCenter=CGRectMake(0.5, 0.5, 0.1, 0.1);
    //按比例放大 不变形
    maskLayer.contentsScale=[UIScreen mainScreen].scale;
    
    //
    CALayer * contentLayer=[CALayer layer];
    contentLayer.mask=maskLayer;
    contentLayer.frame=self.bounds;
    
    self.layer.mask = maskLayer;
    
}