以编程方式切换 UIAlert 控制器

Question

我正在快速创建一个注册对话框，其中包含 3 个文本字段和一个 Switch，并且我成功添加了三个文本字段和两个警报。以下代码显示相同。

 let alertController = UIAlertController(title: "Register", message: "", preferredStyle: .Alert)
    let cancelAction = UIAlertAction(title: "Cancel", style: .Cancel) { (action) in
        // ...

        exit(0)
    }
    alertController.addAction(cancelAction)

    let OKAction = UIAlertAction(title: "Sign UP", style: .Default) { (action) in
        // ...
        let name0 = alertController.textFields![0] as UITextField
        print("Text field: \(name0.text)")

        let email1 = alertController.textFields![1] as UITextField
        print("Text field: \(email1.text)")

        let company2 = alertController.textFields![2] as UITextField
        print("Text field: \(company2.text)")


    }

    alertController.addAction(OKAction)

    alertController.addTextFieldWithConfigurationHandler { (textField) in
        textField.placeholder = "Name"
        textField.keyboardType = .EmailAddress
    }

    alertController.addTextFieldWithConfigurationHandler { (textField) in
        textField.placeholder = "Email"
        textField.secureTextEntry = false
    }

    alertController.addTextFieldWithConfigurationHandler { (textField) in
        textField.placeholder = "Company"
        textField.secureTextEntry = false
    }


            self.presentViewController(alertController, animated: true) {
                // ...
            }

现在我需要以编程方式向警报视图添加一个开关。我们在 Swift2 中执行此操作。有可能吗？我是 Swift 新手。

Answer 1

如果您在 iOS 13 中使用上述 Recycled Steel 的 answer，则可以使用 SF 符号而不是 PNG。它将解决您可能遇到的任何扩展问题。

    checkbox.imageView.tintColor = UIColor.blackColor;
    if (@available(iOS 13.0, *)) {
        [checkbox setImage: [UIImage systemImageNamed:@"square"] forState: UIControlStateNormal];
        [checkbox setImage: [UIImage systemImageNamed:@"checkmark.square"] forState: UIControlStateHighlighted];
        [checkbox setImage: [UIImage systemImageNamed:@"checkmark.square"] forState: UIControlStateSelected];
    }

Answer 2

此答案适用于 Objective C。它不使用文本字段，但确实将 UISwitch 添加到 UIAlertController 中，如主要问题中所述。我没有在 SO 上找到任何可以做到这一点的东西，所以我在这里发布了这个答案，而不是发布另一个会被重复的问题。

此解决方案用于使用户能够对UITableView 菜单（项目列表...）进行排序

感谢@technerd 的回答，我还让UISwitch 更改了UILabel 的文本，它也在同一个UIAlertController 视图上。当UISwitch 值改变时，它在层中使用 KVC（键值编码）将UILabel id 传递给目标操作。 （见代码中setOrderLabelText方法）

我还试图绕过在标题或消息中添加换行符（“\n\n\n\n”）以通过使用约束来人为移动内容的技巧。

我使用了一个水平的UIStackView 来保存UISwitch 和它对应的UILabel，然后使用约束来设置UIStack 的顶部锚点和UIAlertController 视图的高度约束以使其大到足以包含 UIStackView 和 UIAlertController 标题。

我认为不可能获得UIAlertController 的标题高度或操作按钮的高度。所以我想出了在 iPhone X 和 iPad 2 上运行良好的值。与其他 SO 答案一样，我可能会想出一个自制的（或在 GitHub 上找到一个）解决方案来使其更健壮。但既然我已经走了这么远，并且从其他很棒的 SO 答案中得到了很多，我想回馈一点并分享我的结果。

截图如下：

这是代码：

// using KVC, set the label text based on the label tag and toggle the tag
- (void)setOrderLabelText:(UISwitch *)orderSwitch {
    UILabel *label = (UILabel *)[orderSwitch.layer valueForKey:@"label"];

    label.text = label.tag ? @"Ascending" : @"Descending";

    label.tag = label.tag ? 0 : 1;

}

// sort the data based on the user's selections
- (IBAction)sort:(UIButton *)sortButton {    
    UILabel *label = [[UILabel alloc] init];
    label.text = @"Ascending";
    label.textColor = UIColor.grayColor;
    label.tag = 0;
    [label sizeToFit];

    UISwitch *orderSwitch = [[UISwitch alloc] init];
    orderSwitch.on = YES;
    [orderSwitch setOn:YES animated:YES];

    // allow the switch to change the text in the label using KVC (key-value coding)
    [orderSwitch addTarget:self action:@selector(setOrderLabelText:) forControlEvents:UIControlEventValueChanged];
    [orderSwitch.layer setValue:label forKey:@"label"];

    UIStackView *stackView = [[UIStackView alloc] init];
    stackView.axis = UILayoutConstraintAxisHorizontal;
    stackView.spacing = 8;

    [stackView addArrangedSubview:orderSwitch];
    [stackView addArrangedSubview:label];

    UIAlertController *alert = [UIAlertController
                                alertControllerWithTitle: @"Sort Projects By"
                                message: nil
                                preferredStyle:UIAlertControllerStyleAlert];

    UIAlertAction *createdButton = [UIAlertAction
                                  actionWithTitle:@"Created"
                                  style:UIAlertActionStyleDestructive
                                  handler:^(UIAlertAction * action) {
                                      [self sortBy:@"created" ascending:orderSwitch.isOn];
                                  }];
    UIAlertAction *titleButton = [UIAlertAction
                                  actionWithTitle:@"Title"
                                  style:UIAlertActionStyleDestructive
                                  handler:^(UIAlertAction * action) {
                                      [self sortBy:@"title" ascending:orderSwitch.isOn];
                                  }];
    UIAlertAction *subtitleButton = [UIAlertAction
                                  actionWithTitle:@"Subtitle"
                                  style:UIAlertActionStyleDestructive
                                  handler:^(UIAlertAction * action) {
                                      [self sortBy:@"subtitle" ascending:orderSwitch.isOn];
                                  }];
    UIAlertAction *cancelButton = [UIAlertAction
                                   actionWithTitle:@"Cancel"
                                   style:UIAlertActionStyleCancel
                                   handler:^(UIAlertAction * action) {
                                   }];

    // add action buttons to the alert
    [alert addAction:createdButton];
    [alert addAction:titleButton];
    [alert addAction:subtitleButton];
    [alert addAction:cancelButton];

    [alert.view addSubview:stackView];

    // center the stack in the alert
    [stackView.centerXAnchor constraintEqualToAnchor:alert.view.centerXAnchor].active = YES;

    // turn off the autoresizing mask or things get weird
    stackView.translatesAutoresizingMaskIntoConstraints = NO;

    // use a topAnchor constraint to place the stackview, just below the title
    // TODO:  figure out how to get the height of the alert title (use 64 for now)
    [stackView.topAnchor constraintEqualToAnchor:alert.view.topAnchor constant:64].active = YES;

    // layout now to set the view bounds so far - NOTE this does not include the action buttons
    [alert.view layoutIfNeeded];

    // use a height constraint to make the alert view big enough to hold my stack view
    // NOTE:  strange, but this must include the header view AND all the action buttons
    // TODO:  figure out how to get the height of the action buttons (use 52 for each action button for now)
    CGFloat height = alert.view.bounds.size.height + alert.actions.count * 52 + stackView.bounds.size.height;
    [alert.view.heightAnchor constraintEqualToConstant:height].active = YES;

    [self presentViewController:alert animated:YES completion:nil];
}

Answer 3

您可以使用 TextField 的 RightView 来添加按钮。添加一个开关会很好，但开关不适合 TextField 高度，也不能更改高度。为此，您可以添加一个按钮并使用图像来制作一个 TickBox。

我已经从一个项目中删除了这个，所以示例图片比下面的要多一点。

在 ViewController 标头中添加 TextField Delegate

@interface CustomTableViewController : UITableViewController <UITextFieldDelegate>

然后创建您的 AlertController 并添加 TextField

// create an alert controller
UIAlertController *alertWithText = [UIAlertController alertControllerWithTitle:title message:body preferredStyle:UIAlertControllerStyleAlert];

// create the actions handled by each button
UIAlertAction *action1 = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {

}];

UIAlertAction *action2 = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleDestructive handler:^(UIAlertAction * _Nonnull action) {

}];

// add the actions to the alert
[alertWithText addAction:action1];
[alertWithText addAction:action2];

// Establish the weak self reference
__weak typeof(self) weakSelf = self;

[alertWithText addTextFieldWithConfigurationHandler:^(UITextField * _Nonnull textField) {

    // Create button
    UIButton *checkbox = [UIButton buttonWithType:UIButtonTypeCustom];
    [checkbox setFrame:CGRectMake(2 , 2, 18, 18)];  // Not sure about size
    [checkbox setTag:1];
    [checkbox addTarget:weakSelf action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside];

    // Setup image for button
    [checkbox.imageView setContentMode:UIViewContentModeScaleAspectFit];
    [checkbox setImage:[UIImage imageNamed:@"unchecked_checkbox.png"] forState:UIControlStateNormal];
    [checkbox setImage:[UIImage imageNamed:@"checked_checkbox.png"] forState:UIControlStateSelected];
    [checkbox setImage:[UIImage imageNamed:@"checked_checkbox.png"] forState:UIControlStateHighlighted];
    [checkbox setAdjustsImageWhenHighlighted:TRUE];

    // Setup the right view in the text field
    [textField setClearButtonMode:UITextFieldViewModeAlways];
    [textField setRightViewMode:UITextFieldViewModeAlways];
    [textField setRightView:checkbox];

    // Setup Tag so the textfield can be identified
    [textField setTag:-1];
    [textField setDelegate:weakSelf];

    // Setup textfield
    [textField setText:@"Essential"];  // Could be place holder text

}];

[self presentViewController:alertWithText animated:YES completion:nil];

如果您纯粹希望该行成为一个勾号，则需要停止编辑文本字段。

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField{
    if(textField.tag == -1){
        return NO;
    }

    return YES;
} 

以及您对按钮的操作

-(void)buttonPressed:(UIButton*)sender {

    if(sender.selected){
        [sender setSelected:FALSE];
    } else {
        [sender setSelected:TRUE];
    }
}

这里还有一些复选框图像（有很多，您甚至可以切换并尝试制作动画）。

Answer 4

这可能会对您有所帮助。

在上述代码中alertController.addAction(OKAction)之后添加此方法调用alertController.view.addSubview(createSwitch())。

func createSwitch () -> UISwitch{


    let switchControl = UISwitch(frame:CGRectMake(10, 20, 0, 0));
    switchControl.on = true
    switchControl.setOn(true, animated: false);
    switchControl.addTarget(self, action: "switchValueDidChange:", forControlEvents: .ValueChanged);
    return switchControl
}

func switchValueDidChange(sender:UISwitch!){

    print("Switch Value : \(sender.on))")
}

输出：