一、切圆角

1.使用layer. cornerRadius

 view.layer.cornerRadius = 10;
 view.layer.masksToBounds = YES;

2.贝塞尔曲线切

- (void)layoutSubviews{
   [super layoutSubviews];
   UIRectCorner rec = UIRectCornerTopLeft | UIRectCornerTopRight   UIRectCornerBottomLeft | UIRectCornerBottomRight;
   UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:self.bounds byRoundingCorners:rec cornerRadii:CGSizeMake(15, 15)];
   CAShapeLayer *maskLayer = [[CAShapeLayer alloc]init];
   maskLayer.frame = self.bounds;
   maskLayer.path = maskPath.CGPath;
   self.layer.mask = maskLayer;
   [self layoutIfNeeded];
}

二、圆角与阴影共存

1.设置阴影时圆角masksToBounds = NO，view内部做圆角切割

UIView *view= [[UIViewalloc] init];
view.backgroundColor = UIColor.whiteColor;
view.layer.cornerRadius = 10;
// bgView.layer.masksToBounds = YES;
view.layer.shadowColor = [UIColor.blackColor colorWithAlphaComponent:0.05].CGColor;
view.layer.shadowOffset=CGSizeMake(0,5);
view.layer.shadowOpacity = 1;
view.layer.cornerRadius = 10;

2.视图底部添加layer

- (UIView *)shadowView
{
    UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
    view.backgroundColor = UIColor.whiteColor;
    view.layer.shadowOffset = CGSizeMake(0, 0);
    view.layer.shadowColor = [UIColor.blackColor colorWithAlphaComponent:0.05].CGColor;
    view.layer.shadowOpacity = 1;

    CALayer *sublayer =[CALayer layer];
    sublayer.frame = view.frame;
    sublayer.backgroundColor = UIColor.lightGrayColor.CGColor;
    sublayer.cornerRadius = 2;
    sublayer.masksToBounds = YES;
    [view.layer addSublayer:sublayer];
    return view;
}

3.视图底部添加view

- (void)shadowView
{
    UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
    view.layer.cornerRadius = 10;
    view.layer.masksToBounds = YES;

    UIView *layerView = [[UIView alloc] initWithFrame:view.frame];
    layerView.layer.shadowOffset = CGSizeMake(0, 0);
    layerView.layer.shadowColor = [UIColor.blackColor colorWithAlphaComponent:0.05].CGColor;
    layerView.layer.shadowOpacity = 0.5f;

    [self addSubview:layerView];
    [selfaddSubview:view];
}

4.贝塞尔曲线结合layer阴影

在父视图的drawRect方法上增加创建UIBezierPath，并设置圆角属性，设置完成后赋值给指定圆角和阴影的视图shadowPath

- (void)drawRect:(CGRect)rect {
    UIBezierPath *recPath = [UIBezierPath bezierPathWithRoundedRect:self.view. cornerRadius:10];
    self.view.layer.shadowPath = recPath.CGPath;
}

- (instancetype)init
{
    self = [super init];
    if (self) {
        self.view = [[UIView alloc] initWithFrame:CGRectMake(0 , 0, 50, 100)];
        self.view.layer.shadowOpacity = 1;
        self.view.layer.shadowColor = UIColor.redColor.CGColor;
        self.view.layer.shadowOffset = CGSizeMake(0, 0);
        [self self.view];
    }
    return self;
}

注：如果是SDAutoLayout或者Masonry 设置的布局，在layoutIfNeeded之后在设置CALayer