带有负数的 UIKeyboardTypeDecimalPad

Question

我正在开发一个 iOS 应用程序，该应用程序要求用户使用键盘类型 UIKeyboardTypeDecimalPad 将数字输入 UITextField。但是我刚刚意识到不支持输入负数，这是应用程序的要求。

关于如何实现这一点的任何想法或想法？

Answer 1

您可以使用 UIToolbar 作为 UITextField 的输入附件视图，并放置一个带有“+/-”（加/减号）的按钮。

UIToolbar *toolbar = [[UIToolbar alloc]initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, 44)];
UIBarButtonItem *plusMinusBbi = [[UIBarButtonItem alloc]initWithTitle:@"+/-" style:UIBarButtonItemStylePlain target:self action:@selector(togglePositiveNegative:)];
toolbar.items = @[plusMinusBbi];
self.textField.inputAccessoryView = toolbar;

Answer 2

我不相信这样的事情现在是可能的（因为 Apple 还没有实现它）。唯一的选择是设计自己的键盘或使用完整的 ASCII 键盘。

Answer 3

据我所知，苹果还没有实现这样的标准键盘。但是，可以将 UIButtons 添加到任何键盘窗口。 this link should help，或类似教程this link should also help

基本上你注册一个 NSNotificationListener 来监听键盘的到来。抓住键盘框架并将 UIButton 添加到其视图中。上面的链接不是我们想要的，但它是正确的想法。

在 appDelegate 中，

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidShow:) name:UIKeyboardDidShowNotification object:nil];

    - (void)keyboardDidShow:(NSNotification *)note
    {
// Get the Very Top Window on the Display. That's where the Keyboard is.
NSInteger topWindow = [[[UIApplication sharedApplication] windows] count] - 1;
UIWindow *keyboard = [[[UIApplication sharedApplication] windows] objectAtIndex:topWindow];
// If the dot has not been created (first time the keyboard has been displayed) create it.
if (self.dot == nil)
    {
    self.dot = [UIButton buttonWithType:UIButtonTypeCustom];
    // Make the dot a subview of the view containing the keyboard.
    [keyboard addSubview:self.dot];
    // Place the dot in the correct location on the keyboard.
    [self.dot setFrame:CGRectMake(0, 427, 106, 53)];
    // Set the overlay graphics. (Use TransDecimalDown.png and TransDecimalUp.png for the Alert Style Keyboard.
    [self.dot setImage:[UIImage imageNamed:@"DecimalUp.png"] forState:UIControlStateNormal];
    [self.dot setImage:[UIImage imageNamed:@"DecimalDown.png"] forState:UIControlStateHighlighted];
    // Give the dot something to do when pressed.
    [self.dot addTarget:self action:@selector(sendDecimal:)  forControlEvents:UIControlEventTouchUpInside];
}
// Bring the dot to the front of the keyboard.
[keyboard bringSubviewToFront:self.dot];
    }

    - (void)sendDecimal:(id)sender {
// Post a notification that the dot has been pressed. Observing view controllers are then responsible for adding the actual decimal.
[[NSNotificationCenter defaultCenter] postNotificationName:@"DecimalPressed" object:nil];
// Play the Keyboard Click. If the user has these sound effects turned off, the decimal will still click. Sorry.  :(  (Also, doesn't seem to work on the simulator, no keyboard clicks seem to.)
AudioServicesPlaySystemSound(0x450);
    }

对不起，糟糕的代码格式，但你明白了 :)

Answer 4

func addToolbar() {
    let toolbar = UIToolbar()
    toolbar.sizeToFit()
    let plusMinusButton = UIBarButtonItem(title: "+/-", style: .done, target: self, action: #selector(plusMinusAction))
    plusMinusButton.tintColor = .black
    plusMinusButton.width = UIScreen.main.bounds.width / 3
    toolbar.items = [plusMinusButton]
    toolbar.barTintColor = #colorLiteral(red: 0.7812563181, green: 0.8036255836, blue: 0.8297665119, alpha: 1)
    toolbar.isTranslucent = false
    myField.inputAccessoryView = toolbar
}

@objc func plusMinusAction() {
    let text = myField.text ?? ""
    if text.hasPrefix("-") {
        myField.text = String(text.suffix(text.count - 1))
    } else {
        myField.text = "-\(text)"
    }
}

Answer 5

这显然不是我的最佳答案.. 但我无法删除它，因为它被接受了。

希望这段代码对您有所帮助：

如果你想要一个负数，只需使用“-”

NSString *fieldString = [NSString stringWithFormat:@"%@",Textfield.text];

        NSLog(@"%@",fString);

        int fieldValue;
        value = [fString intValue];
        NSLog(@"%d",fieldValue);

这适用于十进制数

            double fieldValue;
            value = [fString doubleValue];
            NSLog(@"%f",fieldValue);

Answer 6

为了完成我使用带有文本字段的“.inputAccessoryView”来完成的任务

在 viewDidLoad 上

self.textField.inputAccessoryView = [self accessoryViewForTextField:self.textField];

然后

- (UIView *)accessoryViewForTextField:(UITextField *)textField{
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 44)];
view.backgroundColor = [UIColor lightGrayColor];

UIButton *minusButton = [UIButton buttonWithType:UIButtonTypeCustom];
UIButton *doneButton = [UIButton buttonWithType:UIButtonTypeCustom];
[minusButton setTitle:@"-" forState:UIControlStateNormal];
[doneButton setTitle:NSLocalizedString(@"Done", @"Done") forState:UIControlStateNormal];
minusButton.backgroundColor = [UIColor magentaColor];
doneButton.backgroundColor = [UIColor blueColor];
CGFloat buttonWidth = view.frame.size.width/3;
minusButton.frame = CGRectMake(0, 0, buttonWidth, 44);
doneButton.frame = CGRectMake(view.frame.size.width - buttonWidth, 0, buttonWidth, 44);

[minusButton addTarget:self action:@selector(minusTouchUpInside:) forControlEvents:UIControlEventTouchUpInside];
[doneButton addTarget:self action:@selector(doneTouchUpInside:) forControlEvents:UIControlEventTouchUpInside];

[view addSubview:minusButton];
[view addSubview:doneButton];

return view;

}

这将在键盘上方添加一个自定义视图作为其中的一部分

终于得到'减号'

#pragma mark - IBActions

- (IBAction)minusTouchUpInside:(id)sender
{
NSString *value = self.textField.text;
if (value.length > 0) {
    NSString *firstCharacter = [value substringToIndex:1];
    if ([firstCharacter isEqualToString:@"-"]){
        self.textField.text = [value substringFromIndex:1];
    }else{
        self.textField.text = [NSString stringWithFormat:@"-%@", value];
    }
}
}

- (IBAction)doneTouchUpInside:(id)sender
{
    [self.textField resignFirstResponder];
}