Question

我在.h文件中添加了委托UITextFieldDelegate

然后在 viewDidLoad 下的.m文件中：

[self textField:self.comment shouldChangeTextInRange:NSMakeRange(0,10) replacementText:@""];

然后添加了函数：

- (BOOL)textField:(UITextField *)textField shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{

   if(textField.text.length >= 10)
   {
       return NO;
   }

    return YES;

}

我的目标是将键盘输入限制为10个字符的文本字段？我做错了什么或如何实现？

Answer 1

这适用于退格和复制＆amp;糊

#define MAXLENGTH 10
- (BOOL)textField:(UITextField *) textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    NSUInteger oldLength = [textField.text length];
    NSUInteger replacementLength = [string length];
    NSUInteger rangeLength = range.length;
    NSUInteger newLength = oldLength - rangeLength + replacementLength;
    BOOL returnKey = [string rangeOfString: @"\n"].location != NSNotFound;
    return newLength <= MAXLENGTH || returnKey;
}

Answer 2

在[self textField:self.comment shouldChangeTextInRange:NSMakeRange(0,10) replacementText:@""];中删除或评论此行viewDidLoad。

在yourtextfield.delegate = self;

中添加viewDidLoad

并实现以下委托方法，

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{

    //allow back space
    if (range.length == 0 && [string length] == 0) {
        return YES;
    }

    if(textField.text.length >= 10)
    {
        return NO;
    }
    else{
        return YES;
    }
}

希望，这会有所帮助：）

Answer 3

首先，你不应该明确地调用方法＆＃34; shouldChangeCharactersInRange :.当您在self.comment TextFiled中键入文本时，将调用此委托方法，前提是您已通过声明分配了委托，

self.comment.delegate = self.

您可以在xib或.m文件中指定委托。

您在shouldChangeCharactersInRange方法中添加的代码对于将输入屏蔽为10个字符是正确的。

希望这会有所帮助。谢谢。

Answer 4

public func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {

    if(range.length + range.location > textField.text?.characters.count)
    {
        return false
    }

    let newLength = (textField.text?.characters.count)! + string.characters.count - range.length;
    return newLength <= self.maximumCharacterAllowed
}

Answer 5

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{

    if (textField == self.textField)
    {
        NSUInteger newLength = [textField.text length] + [string length] - range.length;
        return (newLength > 10) ? NO : YES;
    }
    return YES;
}

Answer 6

使用此代码

#define KMAX_CHAR_LENGTH 20
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    if (textField.text.length >= KMAX_CHAR_LENGTH && range.length == 0) {
        return NO; // do not change text
    } else {
        return YES; // Change Text
    }
}

Answer 7

使用此代码：

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    // Prevent crashing undo bug – see note below.
    if(range.length + range.location > textField.text.length)
    {
        return NO;
    }

    NSUInteger newLength = [textField.text length] + [string length] - range.length;
    return newLength <= 25;
}

如何限制ios中有限字符的UITextField

7 个答案: