Question

我正在创建一个文本字段。

但是文本字段应该只包含字母而不是数字。如何在ios中执行此操作而不检查ASCII值？

Answer 1

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    BOOL canEdit=NO;
    NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString:@"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"];
    for (int i = 0; i < [string length]; i++)
    {
        unichar c = [string characterAtIndex:i];
        if (![myCharSet characterIsMember:c])
        {
            canEdit=NO;
        }
        else
        {
            canEdit=YES;
        }
    }
    return canEdit;
}

Answer 2

以上所有答案都告诉我们如何只允许使用字母表，如果用户按下BackSpace怎么办？这是我的解决方案：

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    const char * _char = [string cStringUsingEncoding:NSUTF8StringEncoding];
    int isBackSpace = strcmp(_char, "\b");

    if (isBackSpace == -8) {
        NSLog(@"Backspace was pressed");
        return YES;
    }

    BOOL canEdit=NO;
    NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString:@"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz or all Character set you like!!!"];
    for (int i = 0; i < [string length]; i++)
    {
        unichar c = [string characterAtIndex:i];
        if (![myCharSet characterIsMember:c])
        {
            canEdit=NO;
        }
        else
        {
            canEdit=YES;
        }
    }
 return canEdit;

}

Answer 3

您需要使用委托方法shouldChangeTextInRange - 每次文本更改时系统会自动调用它。在这种方法中，你需要像这样审查textField中的输入。

为了调用此方法，您需要声明您的类在类.h文件中实现协议（即@interface MyClass : UIViewController <UITextFieldDelegate>），并将文本字段的委托设置为您的类的实例。 / p>

-(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{

   NSCharacterSet *nonNumberSet = [[NSCharacterSet characterSetWithCharactersInString:@"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"] invertedSet];

   NSString *trimmedReplacement =
        [[ text  componentsSeparatedByCharactersInSet:nonNumberSet]
         componentsJoinedByString:@""];

   return ([text stringByTrimmingCharactersInSet:nonNumberSet].length > 0); 

}

Answer 4

我最初从这个问题中的一个答案中得到了代码，但是当不允许退格和空格时修改它。以下代码块仅允许使用字母，空格和退格。默认ios键盘中的数字和特殊字符将被忽略。

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    if ([string isEqualToString:@""]) {
        NSString *originalString = textField.text;
        NSInteger newLength = [textField.text length];
        if (originalString.length > newLength)
            myTextfield.text = [originalString substringToIndex:newLength];
        return YES;
    }
    else{
        BOOL canEdit=NO;
        NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString:@"1234567890-/:;()&@\".,?!'[]{}#%^*+=_\\|~<>$£₹€•"];
        for (int i = 0; i < [string length]; i++)
        {
            unichar c = [string characterAtIndex:i];
            if ([myCharSet characterIsMember:c])
            {
                canEdit=NO;
            }
            else
            {
                canEdit=YES;
            }
        }
        return canEdit;
    }
}

仅允许UITextField的字母表

4 个答案: