textField限制只能输入数字

//是否允许输入
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    return [self validateNumberByRegExp:string];
}

//限制只能输入数字
- (BOOL)validateNumberByRegExp:(NSString *)string {
    BOOL isValid = YES;
    NSUInteger len = string.length;
    if (len > 0) {
        NSString *numberRegex = @"^[0-9.]*$";
        NSPredicate *numberPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", numberRegex];
        isValid = [numberPredicate evaluateWithObject:string];
    }
    return isValid;
}