View 圆角

    /*
     view的layer的实现
     
     通过view的layer直接设置的方式
     */
    UIImageView *redImgView = [[UIImageView alloc]initWithFrame:CGRectMake(50, 50, 100, 100)];
    redImgView.contentMode = UIViewContentModeScaleToFill;
    redImgView.image = [UIImage imageNamed:@"11"];
    redImgView.layer.cornerRadius = redImgView.frame.size.width / 2;
    redImgView.layer.masksToBounds = YES;
    [self.view addSubview:redImgView];
    
    /*
     使用贝塞尔曲线UIBezierPath和Core Graphics实现
     
     BezierPath的实现方式继承UIView，自己实现一个customview
     */
    UIImageView *blueImgView = [[UIImageView alloc]initWithFrame:CGRectMake(50, 200, 100, 100)];
    blueImgView.contentMode = UIViewContentModeScaleAspectFit;
    blueImgView.image = [UIImage imageNamed:@"22"];
    //开始对imageView进行画图
    UIGraphicsBeginImageContextWithOptions(blueImgView.bounds.size, NO, 1.0);
    //使用贝塞尔曲线画出一个圆形图
    [[UIBezierPath bezierPathWithRoundedRect:blueImgView.bounds cornerRadius:blueImgView.frame.size.width] addClip];
    [blueImgView drawRect:blueImgView.bounds];
    blueImgView.image = UIGraphicsGetImageFromCurrentImageContext();
    //结束画图
    UIGraphicsEndImageContext();
    [self.view addSubview:blueImgView];
    
    /*
     使用CAShapeLayer和UIBezierPath实现
     
     通过bezizerpath设置一个路径，加到目标视图的layer上。
     */
    UIImageView *grayImgView = [[UIImageView alloc]initWithFrame:CGRectMake(200, 50, 100, 100)];
    grayImgView.contentMode = UIViewContentModeScaleAspectFill;
    grayImgView.image = [UIImage imageNamed:@"33"];
    UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:grayImgView.bounds byRoundingCorners:UIRectCornerAllCorners cornerRadii:grayImgView.bounds.size];
    CAShapeLayer *maskLayer = [[CAShapeLayer alloc]init];
    //设置大小
    maskLayer.frame = grayImgView.bounds;
    //设置图形样子
    maskLayer.path = maskPath.CGPath;
    grayImgView.layer.mask = maskLayer;
    [self.view addSubview:grayImgView];

image.png

//设置view左侧上UIRectCornerTopLeft 和 左侧下UIRectCornerBottomLeft为5的圆角

UIBezierPath * path = [UIBezierPath bezierPathWithRoundedRect:view.bounds byRoundingCorners:UIRectCornerTopLeft|UIRectCornerBottomLeft cornerRadii:CGSizeMake(5, 5)];

CAShapeLayer * layer = [[CAShapeLayer alloc]init];

layer.frame = view.bounds;

layer.path = path.CGPath;

view.layer.mask = layer;

//设置view 全部角为圆角

viewT.layer.cornerRadius = 10;//设置那个圆角大小

viewT.layer.masksToBounds = YES;//设置YES是保证添加的图片覆盖视图的效果

iOS11 layer新增了maskedCorners属性

typedef NS_OPTIONS (NSUInteger, CACornerMask)
{
  kCALayerMinXMinYCorner = 1U << 0,
  kCALayerMaxXMinYCorner = 1U << 1,
  kCALayerMinXMaxYCorner = 1U << 2,
  kCALayerMaxXMaxYCorner = 1U << 3,
};

//对左下角和右下角进行圆角处理
if (@available(iOS 11.0, *)) {
        view2.layer.maskedCorners = kCALayerMaxXMaxYCorner | kCALayerMaxXMinYCorner;
    } else {
        // Fallback on earlier versions
    }

UIViewContentMode 视图内容的填充方式

@property(nonatomic) UIViewContentMode contentMode;
typedef NS_ENUM(NSInteger, UIViewContentMode) {
    UIViewContentModeScaleToFill,     //填充到整个视图区域，不等比例拉伸。
    UIViewContentModeScaleAspectFit,  //长宽等比填充视图区域，当某一个边到达视图边界的时候就不再拉伸，保证内容的长宽比是不变的同时尽可能的填充视图区域。
    UIViewContentModeScaleAspectFill, //长宽等比填充视图区域，当某一个边到达视图边界的时候还继续拉伸，直到另一个方向达到视图边界。内容的长宽比不变的同时填满整个视图区域，不显示超过的部分。
    UIViewContentModeRedraw,          //重绘视图边界
    UIViewContentModeCenter,          //视图居中
    UIViewContentModeTop,             //视图顶部对齐
    UIViewContentModeBottom,          //视图底部对齐
    UIViewContentModeLeft,            //视图左侧对齐
    UIViewContentModeRight,           //视图右侧对齐
    UIViewContentModeTopLeft,         //视图左上角对齐
    UIViewContentModeTopRight,        //视图右上角对齐
    UIViewContentModeBottomLeft,      //视图左下角对齐
    UIViewContentModeBottomRight,     //视图右下角对齐
};