UItextFiled只能输入数字

- (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;

}