ios - UIButton setTitleColor forState 效果很好，而 setTitle 却不行

Question

从关于 SO 的问题中，我知道使用 setTitle ... forState 更改按钮标签文本是正确的:

[_capturing_button setTitle:@"take photo!" forState:UIControlStateNormal]; 

在我的代码中，用户单击时我想禁用按钮并设置文本“处理”，并在处理完成后启用按钮返回。

但是当禁用按钮时，文本消失。

-(void) initCapturingButton
{
   _capturing_button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    const int width = 150, height = 30;
   _capturing_button.frame = CGRectMake( _main_view.frame.size.width / 2.0 - width / 2.0, 2, width, height );
   _capturing_button.autoresizingMask = UIViewAutoresizingFlexibleLeftMargin | UIViewAutoresizingFlexibleRightMargin;

   [_capturing_button setTitle:@"take photo!" forState:UIControlStateNormal];
   [_capturing_button setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
   //[_capturing_button setTitle:@"processing" forState:UIControlStateDisabled]; 
   [_capturing_button setTitleColor:[UIColor purpleColor] forState:UIControlStateDisabled];

   _capturing_button.enabled = YES;

   [_capturing_button addTarget:self action:@selector(onCapturingButtonClick) forControlEvents:UIControlEventTouchUpInside];
   [_topToolBar addSubview:_capturing_button];

点击按钮时，我只是禁用按钮:

-(void) onCapturingButtonClick
{
     _capturing_button.enabled = NO;
}

处理完成后，启用返回按钮:

  -(void) processingFinished
  {
       _capturing_button.enabled = YES;
  }

使用此代码，当应用程序处于处理模式时，按钮文本为紫色，当处于捕获模式时，颜色为白色。但是，如果我取消注释设置禁用状态标题的行，文本就会消失。

我做错了什么？

Answer 1

由于您只是在 onCapturingButtonClick 方法中禁用而不更改按钮状态，因此您可以设置 UIControlStateNormal 的标题。

-(void) onCapturingButtonClick
{
     [_capturing_button setTitle:@"processing" forState:UIControlStateNormal]; 
     _capturing_button.enabled = NO;
}

然后在你的processingFinished方法中:

  -(void) processingFinished
  {
      [_capturing_button setTitle:@"take photo!" forState:UIControlStateNormal];
       _capturing_button.enabled = YES;
  }

来自UIButton类引用文档:

UIControlStateDisabled

Disabled state of a control. This state indicates that the control is currently > disabled. You can retrieve and set this value through the enabled property.