textField输入手机号，只能输入数字，且不超过11位。（无正则）

#pragma mark 手机号

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

{

    if (textField == self.phoneField) {

        if (string.length == 0) {return YES;}

        if (![self validateNumber:string]) {return NO;}

        

        

        NSInteger existedLength = textField.text.length;

        NSInteger selectedLength = range.length;

        NSInteger replaceLength = string.length;

        if (existedLength - selectedLength + replaceLength > 11) {

            return NO;

        }

    }

    

    return YES;//YES，表示修改生效；NO，表示不做修改，textField的内容不变

}

- (void)textFieldDidChange:(UITextField *)textField

{

    if (textField == self.phoneField) {

        if (textField.text.length > 11) {

            textField.text = [textField.text substringToIndex:11];

        }

    }

}

- (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;

}