如何在Iphone sdk中更改UIButton标题的alpha值？

Question

我需要更改UIButton的alpha值，任何人都可以建议我如何使用它。

我写的按钮代码为：

UIView* buttonView = [[UIView alloc] initWithFrame:CGRectMake(10, 0, 100, 40)];
    buttonView.backgroundColor = [UIColor clearColor];

    backButton = [[UIButton alloc] initWithFrame:CGRectMake(5, 5, 100, 30)];
    [backButton setBackgroundImage:[UIImage imageNamed:@"backbutton_100.png"] forState:UIControlStateNormal];
    [backButton addTarget:self  action:@selector(backAction:)  forControlEvents:UIControlEventTouchUpInside];
    [backButton setTitle:@"  All Customers" forState:UIControlStateNormal];
    backButton.titleLabel.font = [UIFont boldSystemFontOfSize:12];      
    [buttonView addSubview:backButton];

    UIBarButtonItem* leftButton = [[UIBarButtonItem alloc] initWithCustomView:buttonView];
    self.navigationItem.leftBarButtonItem = leftButton;
    [leftButton release];

提前致谢。 Monish。

Answer 1

[backButton setTitleColor:[UIColor colorWithRed:0.3 green:0.6 blue:0.9 alpha:0.5]
//                                set 'alpha' to something less than 1. -----^^^
                 forState:UIControlStateNormal];

Answer 2

Swift 5 版本的 kennytm 的回答：

backButton.setTitleColor(UIColor(red: 0.3, green: 0.6, blue: 0.9, alpha: 0.5), for: .normal)

重要提示：

要对此进行动画处理，需要在“UIButton”上使用“UIView.transition”，因为“UIView.animate”不起作用。