iOS如何重置按钮图像？

Question

我有一些按钮，当按下时，它们从普通按钮变为带有勾号图片的按钮。我遇到的问题是，当按下一个单独的按钮时，我无法将一个勾选的按钮返回到未按下的按钮。这有可能吗？

以下是我的按钮：

    - (IBAction)pickCat:(UIButton *)sender {

    [self deselectAllButtons];

    ((UIButton *)sender).selected = true;

    UIImage *btnImage1 = [UIImage imageNamed:@"white - on.png"];
    [sender setImage:btnImage1 forState:UIControlStateNormal];



    self.catLabel.text = @"WHITE (Hi-Po)";

}
- (IBAction)pickCatb:(UIButton *)sender {

    [self deselectAllButtons];

    ((UIButton *)sender).selected = true;

    UIImage *btnImage1 = [UIImage imageNamed:@"red - on.png"];
    [sender setImage:btnImage1 forState:UIControlStateNormal];


    self.catLabel.text = @"RED (Significant)";

}
- (IBAction)pickCatc:(id)sender {

    UIImage *btnImage1 = [UIImage imageNamed:@"yellow - on.png"];
    [sender setImage:btnImage1 forState:UIControlStateNormal];

    self.catLabel.text = @"YELLOW (Serious)";

}
- (IBAction)pickCatd:(id)sender {

    UIImage *btnImage1 = [UIImage imageNamed:@"green - on.png"];
    [sender setImage:btnImage1 forState:UIControlStateNormal];

    self.catLabel.text = @"GREEN (Important)";

}
- (void)deselectAllButtons
{
    // assuming you have a reference to all your buttons
    self->Btn1.selected = false;
    self->Btn2.selected = false;

}

Answer 1

我喜欢为每个州设置不同的图像：正常和选择。看起来您正在使用Interface Builder，并且使用不同的图像为正常状态和选定状态设置按钮非常容易。

然后在您的代码中，您可以执行以下操作：

- (IBAction)pickImage:(id)sender {

    [self deselectAllButtons];

    sender.selected = true;

    self.locLabel.text = @"Red";

}
- (IBAction)pickImageb:(id)sender {

    [self deselectAllButtons];

    sender.selected = true;

    self.locLabel.text = @"Red";

}

- (void)deselectAllButtons
{
    // assuming you have a reference to all your buttons
    self.btn1.selected = false;
    self.btn2.selected = false;
    ...
}

如果您希望能够在将所有按钮更改为已选中图像之前重置所有按钮，则必须引用您想要影响的所有其他按钮。如果您想获得幻想，请查看Outlet Collections，这样您就可以轻松地遍历IB文件中的一系列按钮，并将其选定状态设置为false。

更新：

以下是您的代码的外观：

- (IBAction)pickCat:(UIButton *)sender {
    [self deselectAllButtons];

    // no need to cast since you changed your method signature.
    // the system now expects sender to be a button
    // ((UIButton *)sender).selected = true;
    sender.selected = true;

    // no need to set the image explicitly. if you did things correctly
    // in IB, you've already told the button which image to use when
    // selected, and which image to use when not (default). when you set
    // the line above (sender.selected = true), that will tell the button
    // to go use the image that you added to the button's selected state in IB
    // UIImage *btnImage1 = [UIImage imageNamed:@"white - on.png"];
    // [sender setImage:btnImage1 forState:UIControlStateNormal];

    self.catLabel.text = @"WHITE (Hi-Po)";
}

- (IBAction)pickCatb:(UIButton *)sender {
    [self deselectAllButtons];

    sender.selected = true;

    self.catLabel.text = @"RED (Significant)";
}

- (IBAction)pickCatc:(id)sender {
    [self deselectAllButtons];

    sender.selected = true;

    self.catLabel.text = @"YELLOW (Serious)";
}

- (IBAction)pickCatd:(id)sender {
    [self deselectAllButtons];

    sender.selected = true;

    self.catLabel.text = @"GREEN (Important)";

}
- (void)deselectAllButtons

{
    // 2 things:
    // 1) I'm not sure about self->Btn1. why not self.Btn1? 
    // 2) it looks like you have 4 buttons (catA, catB, catC, catD). if so, you need to set the selected state for all of them to false
    self->Btn1.selected = false;
    self->Btn2.selected = false;

    self->Btn3.selected = false;
    self->Btn4.selected = false;
}