Question

我正在SWIFT中为iOS8创建一个应用程序，要求用户通过按UIButton输入否定符号。我使用的键盘是DecimalPad，它没有这个选项。我有多个按钮需要使用的文本字段。例如，如果选择了UITextField并且用户按下“ - ”按钮，则会在该文本字段中插入“ - ”。我在UIButton知道哪个UITextField被选中时遇到了麻烦。

任何帮助都将不胜感激。

由于

Answer 1

@property (weak, nonatomic) IBOutlet UIButton *button;
@property (strong, nonatomic) UITextField *selectedTextField;

- (void) viewDidLoad{
    [super viewDidLoad];
    [self.button addTarget:self action:@selector(buttonTapped:) forControlEvents:UIControlEventTouchUpInside];
}

- (void) buttonTapped: (UIButton *) sender{
    self.selectedTextField.text = [NSString stringWithFormat:@"-%@",self.selectedTextField.text];
}

//Make sure you set the delegate of every UITextField to this UIViewController.  
//Also make sure you state that this UIViewController implements the UITextFieldDelegate protocol by inserting <UITextFieldDelegate> in the interface header.
-(void)textFieldDidBeginEditing:(UITextField *)sender{  
    self.selectedTextField = sender; 
}

Answer 2

此解决方案利用insertText:允许您在当前光标所在的位置插入“ - ”。注意：请务必将UITextField代表设置为自己，以使用textFieldDidBeginEditing:和textFieldDidEndEditing:委托方法。

class ViewController: UIViewController, UITextFieldDelegate {

    var selectedTextField:UITextField?

    @IBAction func negativeButtonPress(sender: UIButton) {
        // If a text field stored in selectedTextField
        // insert "-" at the cursor position 
        if let field:UITextField = selectedTextField {
            field.insertText("-")
        }
    }

    // Sets selectedTextField to the current text field
    // when the text field begins editing
    func textFieldDidBeginEditing(textField: UITextField) {
        selectedTextField = textField
    }

    // Sets selectedTextField to the nil
    // when the text field ends editing
    func textFieldDidEndEditing(textField: UITextField) {
        selectedTextField = nil
    }
}

如何使UIButton在所选的UITextField中插入否定符号？

2 个答案: