CAGradientLayer未自动调整大小

Question

我在我的UIImageView上添加了一个CAGradientLayer。我已经在UIImageView上设置了自动调整大小的蒙版，使其在所有边界都是灵活的(灵活的高度，width..etc)。但是，当UIImageView调整大小时，我在imageView上添加的渐变层不会调整大小。为什么会这样呢？代码如下：

CAGradientLayer *imgOverlay = [CAGradientLayer layer];
        CGColorRef startBlueColor = [UIColor colorWithRed:23/255.f green:171/255.f 
                                                     blue:219/255.f alpha:0.8].CGColor; 
        CGColorRef endBlueColor = [UIColor colorWithRed:23/255.f green:171/255.f 
                                                   blue:219/255.f alpha:0.5].CGColor;     
        imgOverlay.colors = [NSArray arrayWithObjects:
                             (id) startBlueColor,
                             (id) endBlueColor,
                             nil];

        imgOverlay.locations = [NSArray arrayWithObjects:
                                [NSNumber numberWithFloat:0.0],
                                [NSNumber numberWithFloat:1.0],
                                nil];

        imgOverlay.startPoint = startPoint;
        imgOverlay.frame = self.backgroundImageView_.bounds;
        imgOverlay.endPoint = endPoint;
        self.imageOverlay = imgOverlay;
        [self.backgroundImageView_.layer addSublayer:self.imageOverlay];

Answer 1

CALayer不支持在iOS上自动调整大小。您必须在layoutSubviews中或任何适当的地方手动实现调整大小。