我写了一个方法来为按钮添加圆角、渐变背景和阴影。这个方法已经用UIButton类写在单独的文件 h 和 m 中，因此可以从应用程序中的任何地方调用它。我不知道为什么，当我回忆起该方法时，按钮出现正确的阴影和圆角，但没有正确的背景渐变。我认为问题与self，即回忆方法有关：按钮属性右阴影和角，但似乎没有将渐变读取为与自身相关。有人可以帮助我吗？谢谢大家。这是代码。
-(void) makeGradient {
//corners this works
CALayer *thisLayer = self.layer;
// Add a border
thisLayer.cornerRadius = 8.0f;
thisLayer.masksToBounds = YES;
thisLayer.borderWidth = 2.0f;
thisLayer.borderColor = self.backgroundColor.CGColor;
//Gradient this doesn't work
btnGradient.cornerRadius=8.f;
CAGradientLayer *btnGradient = [CAGradientLayer layer];
btnGradient.frame = thisLayer.bounds;
btnGradient.colors = [NSArray arrayWithObjects:
(id)[UIColor colorWithWhite:1.0f alpha:0.4f].CGColor,
(id)[UIColor colorWithWhite:1.0f alpha:0.2f].CGColor,
(id)[UIColor colorWithWhite:0.75f alpha:0.2f].CGColor,
(id)[UIColor colorWithWhite:0.4f alpha:0.2f].CGColor,
(id)[UIColor colorWithWhite:1.0f alpha:0.4f].CGColor,
nil];
btnGradient.locations = [NSArray arrayWithObjects:
[NSNumber numberWithFloat:0.0f],
[NSNumber numberWithFloat:0.5f],
[NSNumber numberWithFloat:0.5f],
[NSNumber numberWithFloat:0.8f],
[NSNumber numberWithFloat:1.0f],
nil];
[thisLayer addSublayer:btnGradient];
//Shadow this work
// Give it a shadow
if ([thisLayer respondsToSelector:@selector(shadowOpacity)])
{ // For compatibility, check if shadow is supported
thisLayer.shadowOpacity = 0.7;
thisLayer.shadowColor = [[UIColor blackColor] CGColor];
thisLayer.shadowOffset = CGSizeMake(0.0, 3.0);
// TODO: Need to test these on iPad
if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)] && [[UIScreen mainScreen] scale] == 2)
{
thisLayer.rasterizationScale=2.0;
}
thisLayer.shouldRasterize = YES; // FYI: Shadows have a poor effect on performance
}