使button的背景色变为半透明的但不影响字体的透明度

效果如图:



然而做出这样的效果并不顺利, 刚开始的时候代码如下:

UIButton *backButton = [UIButton buttonWithType:UIButtonTypeSystem];
backButton.backgroundColor = color;
backButton.frame = CGRectMake(18, 610, 380, 50);
[backButton setTitle:@"返回登录" forState:UIControlStateNormal];
[backButton setTitleColor:color forState:UIControlStateNormal];
backButton.alpha = 0.3;
backButton.layer.cornerRadius = 5;
backButton.layer.masksToBounds = YES;
[backButton addTarget:self action:@selector(backLogin:) forControlEvents:UIControlEventTouchUpInside];

执行之后的效果是下面这个样子的:--



对此, 我意识到是设置button透明度的时候, button上字体的透明度也会做出同样的改变. 于是出现上面的情况..

改正后的代码如下:

UIButton *backButton = [UIButton buttonWithType:UIButtonTypeSystem];
backButton.backgroundColor = [UIColor colorWithRed:0 / 255.0 green:180 / 255.0 blue:140 / 255.0 alpha:0.3];
backButton.frame = CGRectMake(18, 610, 380, 50);
[backButton setTitle:@"返回登录" forState:UIControlStateNormal];
[backButton setTitleColor:color forState:UIControlStateNormal];

如代码所示, 将透明度的设置放在backgroundcolor 中, 而不要改变button的alpha属性.执行后的样子就是第一张图显示的样子.

警纪