效果圖如下
exampleImg1.png
實現(xiàn)代碼如下
//blackView為你想加上遮罩的視圖
CGColorRef opaqueBlackColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:1].CGColor;
CGColorRef transparentBalckColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:0.4].CGColor;
//遮罩效果由CAGradientLayer實現(xiàn)
CAGradientLayer * layer = [[CAGradientLayer alloc]init];
layer.frame = CGRectMake(0, 0, WIDTH, self.blackView.bounds.size.height);
//設置漸變的方向
layer.startPoint = CGPointMake(0, 1);
layer.endPoint = CGPointMake(0, 0);
//設置漸變得顏色范圍
layer.colors = @[(__bridge id)opaqueBlackColor,(__bridge id)transparentBalckColor];
[self.blackView.layer insertSublayer:layer atIndex:0];
