iOS中间镂空

一，在要遮罩的UIView上面添加UIImageView，然后生成一张中间镂空的UIImage，赋给UIImageView，设置UIImageView的alphe。

- (UIImage*)holeImageWithContentSize:(CGSize)size cornerRadius:(CGFloat)cR{

    UIGraphicsBeginImageContextWithOptions(size, NO, [UIScreen mainScreen].scale);

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetFillColorWithColor(context, [UIColor blackColor].CGColor);

    CGContextFillRect(context,CGRectMake(0,0, size.width, size.height));

    CGContextAddEllipseInRect(context,CGRectMake((size.width-cR)/2, (size.height-cR)/2, cR, cR));

    CGContextSetBlendMode(context, kCGBlendModeClear);

    CGContextFillPath(context);

    UIImage *returnImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return returnImage;

}

二，绘制一个中间镂空的CAShapeLayer，然后添加在要遮罩的UIView的layer上面。

- (void)holeLayerWithContentSize:(CGSize)size cornerRadius:(CGFloat)cR {

    CAShapeLayer *fillLayer = [CAShapeLayer layer];

    fillLayer.fillRule = kCAFillRuleEvenOdd;

    fillLayer.fillColor= [UIColor blackColor].CGColor;

    fillLayer.opacity=0.3;

    [self.view.layer addSublayer:fillLayer];

    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, size.width, size.height) cornerRadius:0];

    UIBezierPath*circlePath = [UIBezierPath bezierPathWithRoundedRect:CGRectMake((size.width-cR)/2, (size.height-cR)/2, cR, cR)cornerRadius:cR];

    [path appendPath:circlePath];

    [path setUsesEvenOddFillRule:YES];

    fillLayer.path= path.CGPath;

}

三，初始化一个UIView，设置UIView的mask，形成一个中间镂空的UIView，然后添加在要遮罩的UIView上面。

- (void)HoleMaskWithContentSize:(CGSize)size cornerRadius:(CGFloat)cR{

    UIView*maskView = [[UIView alloc]initWithFrame:CGRectMake(0,0, size.width, size.height)];

    maskView.backgroundColor= [UIColor blackColor];

    maskView.alpha=0.3;

    [self.view addSubview:maskView];

    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, size.width, size.height) cornerRadius:0];

    UIBezierPath *roundPath = [[UIBezierPath bezierPathWithRoundedRect:CGRectMake((size.width-cR)/2, (size.height-cR)/2, cR, cR) cornerRadius:cR] bezierPathByReversingPath];

    [path appendPath:roundPath];

    CAShapeLayer *shapeLayer = [CAShapeLayer layer];

    shapeLayer.path= path.CGPath;

    maskView.layer.mask= shapeLayer;

}

四，自定义一个UIView，在- (void)drawRect:(CGRect)rect中绘制中间镂空，然后添加在要遮罩的UIView上面，要注意一点，自定义的UIView的backgroundColor必须设置成clearColor。（注释掉的上下两段代码，是两种生成中间镂空的矩形）

#import "HoleView.h"

@implementation HoleView

- (void)drawRect:(CGRect)rect {

    //    CGContextRef context = UIGraphicsGetCurrentContext();

    //    CGContextAddRect(context, rect);

    //    [[UIColor colorWithWhite:0 alpha:0.3] set];

    //    CGContextFillRect(context, rect);

    //    CGContextClearRect(context, CGRectMake((rect.size.width-100)/2, (rect.size.height-100)/2, 100, 100));

    //    CGContextDrawPath(context, kCGPathFillStroke);

    CGContextRef context = UIGraphicsGetCurrentContext();

    [[UIColor colorWithWhite:0 alpha:0.3] set];

    CGContextAddRect(context, rect);

    CGContextFillPath(context);

    CGContextSetBlendMode(context, kCGBlendModeClear);

    CGContextAddEllipseInRect(context, CGRectMake(100, 100, 200, 200));

    CGContextFillPath(context);

//    [[UIColor colorWithWhite:0 alpha:0.3] setFill];

//    UIRectFill(rect);

//    CGRect holeRection = CGRectMake(100, 200, 200, 200);

//    // 交集

//    CGRect holeiInterSection = CGRectIntersection(holeRection, rect);

//    [[UIColor clearColor] setFill];

//    UIRectFill(holeiInterSection);

}

@end