是否有类似于数字键盘但允许负数的 UITextField 键盘类型？

Question

我在我的 UITextFields 上将 UIKeyboardType 设置为 UIKeyboardTypeNumberPad。但是，这只允许用户输入正整数。我需要用户能够输入负整数或正整数。是否有与 UIKeyboardTypeNumberPad 相同但还包含“-”（减号）符号的 UIKeyboardType，如果没有，我可以创建它吗？

谢谢。

Answer 1

这是一个 Swift 版本，它有一个 +/- 按钮，还有一个用于数字键盘的 Clear 和 Done 按钮。

numeric keyboard screenshot

extension UITextField {

func addNumericAccessory(addPlusMinus: Bool) {
    let numberToolbar = UIToolbar()
    numberToolbar.barStyle = UIBarStyle.default

    var accessories : [UIBarButtonItem] = []

    if addPlusMinus {
        accessories.append(UIBarButtonItem(title: "+/-", style: UIBarButtonItem.Style.plain, target: self, action: #selector(plusMinusPressed)))
        accessories.append(UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: self, action: nil))   //add padding after
    }

    accessories.append(UIBarButtonItem(title: "Clear", style: UIBarButtonItem.Style.plain, target: self, action: #selector(numberPadClear)))
    accessories.append(UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: self, action: nil))   //add padding space
    accessories.append(UIBarButtonItem(title: "Done", style: UIBarButtonItem.Style.plain, target: self, action: #selector(numberPadDone)))

    numberToolbar.items = accessories
    numberToolbar.sizeToFit()

    inputAccessoryView = numberToolbar
}

@objc func numberPadDone() {
    self.resignFirstResponder()
}

@objc func numberPadClear() {
    self.text = ""
}

@objc func plusMinusPressed() {
    guard let currentText = self.text else {
        return
    }
    if currentText.hasPrefix("-") {
        let offsetIndex = currentText.index(currentText.startIndex, offsetBy: 1)
        let substring = currentText[offsetIndex...]  //remove first character
        self.text = String(substring)
    }
    else {
        self.text = "-" + currentText
    }
}

}

Answer 2

烦人的是，没有这样的系统键盘可用。除了创建自定义键盘之外，您最好的选择是UIKeyboardTypeNumbersAndPunctuation，并进行验证以强制输入有效的数字。

Answer 3

添加一个减号作为accesoryView，你需要将你的textField作为一个属性，在这个例子中这个属性是：myTextField;

您需要在创建 myTextField 后添加此代码，b.e.在 viewDidLoad 中：

      UIView *inputAccesoryView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 40)];
// It´s good idea a view under the button in order to change the color...more custom option
inputAccesoryView.backgroundColor = [UIColor whiteColor];

UIButton *minusButton = [[UIButton alloc] initWithFrame:CGRectMake(([UIScreen mainScreen].bounds.size.width-150)/2, 5, 150, 30)];
// configure the button here... you choose.
[minusButton setTitle:@"-" forState:UIControlStateNormal];
[minusButton addTarget:self action:@selector(changeNumberSing) forControlEvents:UIControlEventTouchUpInside];
[inputAccesoryView addSubview:minusButton];

self.myTextField.inputAccessoryView = inputAccesoryView;

并在你的viewController中添加这个按钮的方法：

-(void)changeNumberSing
{
if ([self.myTextField.text hasPrefix:@"-"])
{
    self.myTextField.text = [self.myTextField.text substringFromIndex:1];
}else
{
    self.myTextField.text = [NSString stringWithFormat:@"-%@",self.myTextField.text];
}
}