objective-c - 在objective-c中更改按钮的背景图像？

Question

我的VC 中有一个UIButton这样的单元格UITableView

arrowBtnUp = [UIButton buttonWithType:UIButtonTypeCustom];
arrowBtnUp.frame = CGRectMake(50,(65-19)/2,31, 31);
[arrowBtnUp setBackgroundImage:[UIImage imageNamed:@"arrow_up.png"] forState:UIControlStateNormal];
[arrowBtnUp addTarget:self action:@selector(slideAction) forControlEvents:UIControlEventTouchUpInside];
[cell.contentView addSubview:arrowBtnUp];

这是我的slideAction

-(void) slideAction
{
    [arrowBtnUp setBackgroundImage:[UIImage imageNamed:@"arrow_down.png"] forState:UIControlStateNormal];
    // also tried  with UIControlStateSelected/Highlighted
}

但它没有用。我找到了这个链接但没有帮助。任何建议或样品将不胜感激。

Answer 1

您的代码应该可以工作。无论如何更改您的代码并尝试

-(void) slideAction:(id)sender
{
   [sender setBackgroundImage:[UIImage imageNamed:@"arrow_down.png"] forState:UIControlStateNormal];
}

和

[arrowBtnUp addTarget:self action:@selector(slideAction:) forControlEvents:UIControlEventTouchUpInside];

并确保您的 app bundle 中有 arrow_down.png

Answer 2

问题是您正在重用arrowBtnUpUIButton 的实例。因此，在该slideAction方法中，您不会获得按下的按钮参考。

要在方法中获取引用，slideAction您需要将其作为参数传递。

因此，将代码更改为：

[arrowBtnUp addTarget:self action:@selector(slideAction:) forControlEvents:UIControlEventTouchUpInside];


-(void) slideAction:(UIButton *)myButton
{
   [myButton setBackgroundImage:[UIImage imageNamed:@"arrow_down.png"] forState:UIControlStateNormal];
}

Answer 3

If you're trying to change the button image after a touch, you should use the UIButton's control states. You can assign a background image for each "state" and let UIButton determine which to show.

Answer 4

背景图像与按钮上的图标不同。试试这个：

[_buttonConfirm setImage:[UIImage imageNamed:@"s.png"] forState:UIControlStateNormal];

Answer 5

If you're trying to change the button image after a touch, you should use the UIButton's control states. You can assign a background image for each "state" and let UIButton determine which to show.

[myButton setBackgroundImage:[UIImage imageNamed:@"arrow_up.png"] forState:UIControlStateNormal];
[myButton setBackgroundImage:[UIImage imageNamed:@"arrow_down.png"] forState:UIControlStateSelected];

There is no need to manually switch the background images in your slideAction: target method.