Objective-C：仅限数字文本字段？

Question

  

可能重复：
  Iphone UITextField only integer

我想放置一个只接受数字的文本字段（0-9，甚至不需要小数），但即使使用“数字键盘”输入选项，我仍然会得到一个带有各种符号的键盘。是否有更好的控制，是否有更好的控制我正在做什么，或者我只需要手动验证输入？

Answer 1

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
/* for backspace */    
    if([string length]==0){
       return YES;
    }

/*  limit to only numeric characters  */

    NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
    for (int i = 0; i < [string length]; i++) {
       unichar c = [string characterAtIndex:i];
       if ([myCharSet characterIsMember:c]) {
          return YES;
      }
    }

return NO;
}

Answer 2

代码在某种程度上是不正确的，应该是

/*  limit to only numeric characters  */
NSCharacterSet* numberCharSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
for (int i = 0; i < [string length]; ++i)
{
    unichar c = [string characterAtIndex:i];
    if (![numberCharSet characterIsMember:c])
    {
        return NO;
    }
}

return YES;

Answer 3

以下代码将允许您仅输入数字以及限制可以使用的字符数。

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string 
{
    /*  limit to only numeric characters  */
    NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
    for (int i = 0; i < [string length]; i++) {
        unichar c = [string characterAtIndex:i];
        if ([myCharSet characterIsMember:c]) {
            return YES;
        }
    }

    /*  limit the users input to only 9 characters  */
    NSUInteger newLength = [customTextField.text length] + [string length] - range.length;
    return (newLength > 9) ? NO : YES;
}