我正在尝试向 UImageView 添加阴影

Question

我正在尝试向 UIImage 视图添加投影。我得到一个阴影，但它被剪裁到图像视图的边缘，我不知道为什么，因为我正确地将 uiimageview.clipsToBounds 设置为 NO。下面是代码：

-(void)addShadow
{
   UIGraphicsBeginImageContext(self.frame.size);
   CGContextRef myContext =  UIGraphicsGetCurrentContext();
   float           myColorValues[] = {0, 0, 0, darkness};// 3
   CGColorRef      myColor;// 4
   CGColorSpaceRef myColorSpace;
   CGContextSaveGState(myContext);// 6

   myColorSpace = CGColorSpaceCreateDeviceRGB ();// 9
   myColor = CGColorCreate (myColorSpace, myColorValues);// 10
   CGContextSetShadowWithColor (myContext, myShadowOffset, spread, myColor);// 11
   // Your drawing code here// 12
   // CGContextDrawImage(myContext, rotatingView.frame,imgRef);

   rotatingView.clipsToBounds = NO;
   [rotatingView.image drawInRect:rotatingView.frame
                        blendMode:kCGBlendModeNormal alpha:.5];
   CGColorRelease (myColor);// 13
   CGColorSpaceRelease (myColorSpace); // 14

   UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext();
   CGContextRestoreGState(myContext);
   UIGraphicsEndImageContext();
   rotatingView.image = imageCopy;
}

Answer 1

我相信您传递的 CGContextRef 也设置了剪辑，以防止这种确切的行为。您可能想尝试只添加一个 CALayer：

CALayer                         *layer = [CALayer layer];
CGRect                          bounds = self.bounds;

layer.bounds = bounds;
layer.position = CGPointMake(bounds.size.width / 2 + 5, bounds.size.height / 2 + 5);
layer.backgroundColor = [UIColor colorWithWhite: 0.10 alpha: 0.75].CGColor;
layer.zPosition = -5;

[self.layer addSublayer: layer];