UITextField：密码实现

Question

我有一个 OTP 屏幕，我必须在 4 Diff TextFields 中输入 4 位密码的 OTP，场景是这样的：

1. 每个文本字段的最大字符数限制为 1，当用户在文本字段中输入一个字符时，它应该移动到下一个文本字段。
2. 当用户单击退格时，它应该返回到上一个文本字段以便进行更改。

我已经管理了高达 70% 的工作，但只有当用户输入所有文本字段时，退格才有效。我正在粘贴我的代码。

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    // This allows numeric text only, but also backspace for deletes
    if (string.length > 0 && ![[NSScanner scannerWithString:string] scanInt:NULL])
        return NO;

    NSUInteger oldLength = [textField.text length];
    NSUInteger replacementLength = [string length];
    NSUInteger rangeLength = range.length;

    NSUInteger newLength = oldLength - rangeLength + replacementLength;

    // This 'tabs' to next field when entering digits
    if (newLength == 1) {
        if (textField == _pin1)
        {
            [self performSelector:@selector(setNextResponder:) withObject:_pin2 afterDelay:0];
        }
        else if (textField ==_pin2)
        {
            [self performSelector:@selector(setNextResponder:) withObject:_pin3 afterDelay:0];
        }
        else if (textField == _pin3)
        {
            [self performSelector:@selector(setNextResponder:) withObject:_pin4 afterDelay:0];
        }
    }
    //this goes to previous field as you backspace through them, so you don't have to tap into them individually
    else if (oldLength > 0 && newLength == 0) {
        if (textField ==_pin4)
        {
            [self performSelector:@selector(setNextResponder:) withObject:_pin3 afterDelay:0];
        }
        else if (textField == _pin3)
        {
            [self performSelector:@selector(setNextResponder:) withObject:_pin2 afterDelay:0];
        }
        else if (textField == _pin2)
        {
            [self performSelector:@selector(setNextResponder:) withObject:_pin1 afterDelay:0];
        }
    }        
    return newLength <= 1;
}

- (void)setNextResponder:(UITextField *)nextResponder
{
    [nextResponder becomeFirstResponder];
}

工作：

Answer 1

需要在StoryBoard中给UITextView添加标签。

比如 textField1 = 101,textField2 = 102,textField3 = 103,textField4 = 104

将以下代码放入您的viewcontroller。

- (BOOL)keyboardInputShouldDelete:(UITextField *)textField {
    BOOL shouldDelete = YES;

    if ([textField.text length] == 0 && [textField.text isEqualToString:@""]) {
        long tagValue = textField.tag - 1;
        UITextField *txtField = (UITextField*) [self.view viewWithTag:tagValue];

        [txtField becomeFirstResponder];
    }
    return shouldDelete;
}

以下代码为下一个UItextField焦点。

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    // This allows numeric text only, but also backspace for deletes
    if (string.length > 0 && ![[NSScanner scannerWithString:string] scanInt:NULL])
        return NO;

    if ([textField.text length] == 0) {
        [self performSelector:@selector(changeTextFieldFocusToNextTextField:) withObject:textField afterDelay:0.3];
    }

    return YES;
}

-(void)changeTextFieldFocusToNextTextField:(UITextField*)textField{
    long tagValue = textField.tag + 1;
    UITextField *txtField = (UITextField*) [self.view viewWithTag:tagValue];
    [txtField becomeFirstResponder];
}

样本输出

Grab the solution demo project

Answer 2

原因是当 UITextField 为empty 时，它不会检测到backspace event。

因此要在这种情况下检测退格事件，您必须 Subclass UITextField 并覆盖 deleteBackward 方法。

验证以下链接了解更多详情。

Detect backspace in UITextField

编辑：添加代码。

-将所有 4 个 UITextfield 子类化为以下类。

@protocol MyTextFieldDelegate <NSObject>
@optional
- (void)textFieldDidDelete:(UITextField *)textField;
@end

@interface MyTextField : UITextField<UIKeyInput>

@property (nonatomic, assign) id<MyTextFieldDelegate> myDelegate;
@end

@implementation MyTextField

- (void)deleteBackward {
    [super deleteBackward];

    if ([_myDelegate respondsToSelector:@selector(textFieldDidDelete:)]){
        [_myDelegate textFieldDidDelete:self];
    }
}

@end

-将所有UITextFields的delegate设置为self，并在类中采用MyTextFieldDelegate协议

  _pin1.myDelegate=self;
  _pin2.myDelegate=self;
  _pin3.myDelegate=self;
  _pin4.myDelegate=self;

-现在实现textFieldDidDelete方法如下

- (void)textFieldDidDelete:(UITextField *)textField {
    if (textField ==_pin4)
    {
        [self performSelector:@selector(setNextResponder:) withObject:_pin3 afterDelay:0];
    }
    else if (textField == _pin3)
    {
        [self performSelector:@selector(setNextResponder:) withObject:_pin2 afterDelay:0];
    }
    else if (textField == _pin2)
    {
        [self performSelector:@selector(setNextResponder:) withObject:_pin1 afterDelay:0];
    }
}

希望这会有所帮助。

Answer 3

对于 Swift 3.x

class CodeConfirmController:ViewController,UITextFieldDelegate{

@IBOutlet weak var digitNum1: UITextField!
    @IBOutlet weak var digitNum2: UITextField!
    @IBOutlet weak var digitNum3: UITextField!
    @IBOutlet weak var digitNum4: UITextField!

 override func viewDidLoad() {
        digitNum1.delegate = self
        digitNum2.delegate = self
        digitNum3.delegate = self
        digitNum4.delegate = self
    }

    func keyboardInputShouldDelete(_ textField: UITextField) -> Bool {
        let shouldDelete: Bool = true
        if textField.text?.characters.count == 0 && (textField.text == "") {
            let tagValue: Int = textField.tag - 1
            let txtField: UITextField? = (view.viewWithTag(tagValue) as? UITextField)
            txtField?.becomeFirstResponder()
        }
        return shouldDelete
    }

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        // This allows numeric text only, but also backspace for deletes
        if (string.characters.count ) > 0 && !Scanner(string: string).scanInt32(nil) {
            return false
        }
        if textField.text?.characters.count == 0 {
            perform(#selector(self.changeTextFieldFocus(toNextTextField:)), with: textField, afterDelay: 0.1)
        }
        return true
    }

    func changeTextFieldFocus(toNextTextField textField: UITextField) {
        let tagValue: Int = textField.tag + 1
        let txtField: UITextField? = (view.viewWithTag(tagValue) as? UITextField)
        txtField?.becomeFirstResponder()
    }
}