限制UITextField只可以输入数字

今天项目中有个文本框需要只可以输入数字的需求，首先在.xib中将UITextField的Keyboard设置为Number Pad，但是使用时键盘会切回别的键盘无法对内容进行校验。通过神奇的百度我知道了通过以下方法可以解决这样的问题：

首先让.xib的viewController实现UITextFieldDelegate然后和想要校验的控件关联。

然后将下列代码粘贴到类中即可。

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    return [self validateNumber:string];
}
  
- (BOOL)validateNumber:(NSString*)number {
    BOOL res = YES;
    NSCharacterSet* tmpSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
    int i = 0;
    while (i < number.length) {
        NSString * string = [number substringWithRange:NSMakeRange(i, 1)];
        NSRange range = [string rangeOfCharacterFromSet:tmpSet];
        if (range.length == 0) {
            res = NO;
            break;
        }
        i++;
    }
    return res;
}

还有一种方式，以下这种方式我还没有试过但是我找到了就分享出来吧：

1.定义常量以备使用

1	`#define NUMBERS @"0123456789"`

- (BOOL)textField:(UITextField*)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString*)string
{
        NSCharacterSet*cs;
        cs = [[NSCharacterSetcharacterSetWithCharactersInString:NUMBERS] invertedSet];
        NSString*filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];
        BOOLbasicTest = [string isEqualToString:filtered];
        if(!basicTest) {
              
            UIAlertView* alert = [[UIAlertViewalloc] initWithTitle:@"提示"
                                                            message:@"请输入数字"
                                                           delegate:nil
                                                  cancelButtonTitle:@"确定"
                                                  otherButtonTitles:nil];
              
            [alert show];
            returnNO;
              
        }
    returnYES;
}