键盘格式

 keyboardType = UIKeyboardTypeDecimalPad;

pragma mark- UITextFieldDelegate//在这个代理方法//限定9位、小数点后两位、开头只能输入一个0、只能有一位小数点

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
       NSString *toString = [textField.text stringByReplacingCharactersInRange:range withString:string];
    if (toString.length > 0) {
        
//        NSString *stringRegex = @"(\\+|\\-)?(([0]|(0[.]\\d{0,2}))|([1-9]\\d{0,4}(([.]\\d{0,2})?)))?";//(带正负号的)
        NSString *stringRegex = @"(([0]|(0[.]\\d{0,2}))|([1-9]\\d{0,8}(([.]\\d{0,2})?)))?";//一般格式 d{0,8} 控制位数
        NSPredicate *money = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", stringRegex];
        BOOL flag = [money evaluateWithObject:toString];
        if (!flag)
            return NO;
        
    }
    return YES;
    
}

转载：https://www.jianshu.com/p/70181c6cfbf9