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我知道有可能通過使用drawrect方法並通過調整CGRect UIColor的alpha值來例如在UIImagePickerController上添加透明/半透明覆蓋視圖。但是有可能獲得模糊的效果而不是半透明的效果？我希望我已經清楚... 謝謝！UIImagePickerController模糊覆蓋視圖？
編輯（添加代碼）
- (void)drawRect:(CGRect)rect{
CGFloat toolbarSize = UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad ? 0 : 80;
CGFloat width = CGRectGetWidth(self.frame);
CGFloat height = CGRectGetHeight(self.frame) - toolbarSize;
CGFloat heightSpan = floor(height/2 - self.cropSize.height/2);
CGFloat widthSpan = floor(width/2 - self.cropSize.width/2);
//fill outer rect
[[UIColor colorWithRed:0. green:0. blue:0. alpha:0.5] set];
UIRectFill(self.bounds);
//fill inner border
[[UIColor colorWithRed:1. green:1. blue:1. alpha:0.5] set];
UIRectFrame(CGRectMake(widthSpan - 1, heightSpan - 1, self.cropSize.width + 2, self.cropSize.height + 2));
//fill inner rect
[[UIColor clearColor] set];
UIRectFill(CGRectMake(widthSpan, heightSpan, self.cropSize.width, self.cropSize.height));
}
}