将 maxlength 设置为特定的 UITextField

Question

我尝试将 maxlength 设置为我的 UITextfield，但它也会影响我的其他 UITextfield。

我尝试使用：

- (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;
}

我只想将最大长度设置为特定的 uitextfield。

Answer 1

它适用于 swift，试试这个

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let length = ((txtPhoneNumber.text?.count)! - range.length) + string.count
    if length <= 9 {
        return true
    }
    return false
}

Answer 2

首先，检查编辑文本字段。然后检查字符串的长度

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

    /// always allow other textfields
    if (textField != specificTextfield) {
         return YES;
    }

    /// check max length

    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;
}

参考：Set UITextField Maximum Length

Answer 3

将标签添加到您的文本字段。并在委托 shouldChangeCharactersInRange 方法中检查文本字段是否对应于特定标签。

#define MAXLENGTH 10

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
if (textField.tag == 1){
    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;
}
return true;
}

将 maxlength 设置为特定的 UITextField

Set maxlength to specific UITextField

objective-c

uitextfield

ios