UIView实现阴影加圆角

原文链接
参考链接一
参考链接二

在给view加阴影并且同时加圆角的时候，会遇到经典的masksToBounds问题，masksToBounds为YES或NO时，仅阴影或圆角生效，不能同时生效。为解决此问题，解决办法是加一层layer来实现。
要点：
1. shadow加到单独的layer上面，layer和view.layer同frame，并且是路经阴影额？，然后加到view的底层；
2. 在view的layer上面加cornerRadius。
具体如下：

/*








 周边加阴影，并且同时圆角








 */








+ (void)addShadowToView:(UIView *)view








            withOpacity:(float)shadowOpacity








           shadowRadius:(CGFloat)shadowRadius








        andCornerRadius:(CGFloat)cornerRadius








{








    //////// shadow /////////








    CALayer *shadowLayer = [CALayer layer];








    shadowLayer.frame = view.layer.frame;








    








    shadowLayer.shadowColor = [UIColor blackColor].CGColor;//shadowColor阴影颜色








    shadowLayer.shadowOffset = CGSizeMake(0, 0);//shadowOffset阴影偏移，默认(0, -3),这个跟shadowRadius配合使用








    shadowLayer.shadowOpacity = shadowOpacity;//0.8;//阴影透明度，默认0








    shadowLayer.shadowRadius = shadowRadius;//8;//阴影半径，默认3








    








    //路径阴影








    UIBezierPath *path = [UIBezierPath bezierPath];








    








    float width = shadowLayer.bounds.size.width;








    float height = shadowLayer.bounds.size.height;








    float x = shadowLayer.bounds.origin.x;








    float y = shadowLayer.bounds.origin.y;








    








    CGPoint topLeft      = shadowLayer.bounds.origin;








    CGPoint topRight     = CGPointMake(x + width, y);








    CGPoint bottomRight  = CGPointMake(x + width, y + height);








    CGPoint bottomLeft   = CGPointMake(x, y + height);








    








    CGFloat offset = -1.f;








    [path moveToPoint:CGPointMake(topLeft.x - offset, topLeft.y + cornerRadius)];








    [path addArcWithCenter:CGPointMake(topLeft.x + cornerRadius, topLeft.y + cornerRadius) radius:(cornerRadius + offset) startAngle:M_PI endAngle:M_PI_2 * 3 clockwise:YES];








    [path addLineToPoint:CGPointMake(topRight.x - cornerRadius, topRight.y - offset)];








    [path addArcWithCenter:CGPointMake(topRight.x - cornerRadius, topRight.y + cornerRadius) radius:(cornerRadius + offset) startAngle:M_PI_2 * 3 endAngle:M_PI * 2 clockwise:YES];








    [path addLineToPoint:CGPointMake(bottomRight.x + offset, bottomRight.y - cornerRadius)];








    [path addArcWithCenter:CGPointMake(bottomRight.x - cornerRadius, bottomRight.y - cornerRadius) radius:(cornerRadius + offset) startAngle:0 endAngle:M_PI_2 clockwise:YES];








    [path addLineToPoint:CGPointMake(bottomLeft.x + cornerRadius, bottomLeft.y + offset)];








    [path addArcWithCenter:CGPointMake(bottomLeft.x + cornerRadius, bottomLeft.y - cornerRadius) radius:(cornerRadius + offset) startAngle:M_PI_2 endAngle:M_PI clockwise:YES];








    [path addLineToPoint:CGPointMake(topLeft.x - offset, topLeft.y + cornerRadius)];








    








    //设置阴影路径








    shadowLayer.shadowPath = path.CGPath;








    








    //////// cornerRadius /////////








    view.layer.cornerRadius = cornerRadius;








    view.layer.masksToBounds = YES;








    view.layer.shouldRasterize = YES;








    view.layer.rasterizationScale = [UIScreen mainScreen].scale;








    








    [view.superview.layer insertSublayer:shadowLayer below:view.layer];








}

效果：

PS: 
1. label文案加阴影：

- (void)addShadowForPlaceHolder








{








    if (!(_placeHolderLabel.text.length > 0)) {








        return;








    }








    








    NSShadow *shadow = [NSShadow new];








    shadow.shadowBlurRadius = 0.5f;








    shadow.shadowOffset = CGSizeMake(0.0f, 0.5f);








    shadow.shadowColor = [[UIColor blackColor] colorWithAlphaComponent:0.4f];








    NSAttributedString *attributedText = [[NSAttributedString alloc] initWithString:_placeHolderLabel.text attributes:@{NSShadowAttributeName : shadow}];








    _placeHolderLabel.attributedText = attributedText;








}

2. view加普通阴影：

    _descTextView = [UITextView new];








    _descTextView.textColor = kCZUIWhiteColor;








    _descTextView.font = _fontLarge;








    _descTextView.scrollEnabled = NO;








    _descTextView.text = _liveDesc;








    _descTextView.translatesAutoresizingMaskIntoConstraints = NO;








    _descTextView.delegate = self;








    _descTextView.textContainerInset = UIEdgeInsetsZero;








    CZ_SetUIViewBackgroundColor(_descTextView, _placeHolderLabel.backgroundColor);








    _descTextView.enablesReturnKeyAutomatically = NO;








    _descTextView.layer.shadowColor = [UIColor blackColor].CGColor;








    _descTextView.layer.shadowOpacity = 0.4;








    _descTextView.layer.shadowRadius = 0.5f;








    _descTextView.layer.shadowOffset = CGSizeMake(0.0f, 0.5f);








    _descTextView.layer.shouldRasterize = YES;








    _descTextView.layer.rasterizationScale = CZ_MainScreen().scale;

3. view加普通路经阴影

- (void)addShadow:(UIView *)view








{








    view.layer.shadowColor = [UIColor blackColor].CGColor;//shadowColor阴影颜色








    view.layer.shadowOffset = CGSizeMake(0, 0);//shadowOffset阴影偏移，默认(0, -3),这个跟shadowRadius配合使用








    view.layer.shadowOpacity = 0.3;//0.8;//阴影透明度，默认0








    view.layer.shadowRadius = 2;//8;//阴影半径，默认3








    








    //路径阴影








    UIBezierPath *path = [UIBezierPath bezierPath];








    








    float width = view.bounds.size.width;








    float height = view.bounds.size.height;








    float x = view.bounds.origin.x;








    float y = view.bounds.origin.y;








    








    CGPoint topLeft      = view.bounds.origin;








    CGPoint topRight     = CGPointMake(x + width, y);








    CGPoint bottomRight  = CGPointMake(x + width, y + height);








    CGPoint bottomLeft   = CGPointMake(x, y + height);








    








    CGFloat offset = 0.f;








    [path moveToPoint:CGPointMake(topLeft.x - offset, topLeft.y - offset)];








    [path addLineToPoint:CGPointMake(topRight.x + offset, topRight.y - offset)];








    [path addLineToPoint:CGPointMake(bottomRight.x + offset, bottomRight.y + offset)];








    [path addLineToPoint:CGPointMake(bottomLeft.x - offset, bottomLeft.y + offset)];








    [path addLineToPoint:CGPointMake(topLeft.x - offset, topLeft.y - offset)];








    








    //设置阴影路径








    view.layer.shadowPath = path.CGPath;








}