金額輸入限制（小數(shù)點后兩位+最多不超過10億）

代碼：
初始化

        _moneyTextField = [[UITextField alloc] init];
        _moneyTextField.font = [UIFont systemFontOfSize:14];
        _moneyTextField.placeholder = @"請?zhí)顚懩繕?biāo)";
        _moneyTextField.textColor = UIColorHex(5C5C5C);
        _moneyTextField.borderStyle = UITextBorderStyleNone;
        _moneyTextField.textAlignment = NSTextAlignmentLeft;
        _moneyTextField.keyboardType = UIKeyboardTypeDecimalPad;
        [self.contentView addSubview:_moneyTextField];
        _moneyTextField.delegate = self;
        [_moneyTextField addTarget:self action:@selector(textfieldTextDidChange:) forControlEvents:UIControlEventEditingChanged];
        [_moneyTextField addTarget:self action:@selector(textfieldEditingDidBegin:) forControlEvents:UIControlEventEditingDidBegin];
        [_moneyTextField addTarget:self action:@selector(textfieldEditingDidEnd:) forControlEvents:UIControlEventEditingDidEnd];

/**
 金額的判斷，不超過十億+小數(shù)點后兩位
 */
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if (textField == _moneyTextField) {
        NSScanner      *scanner    = [NSScanner scannerWithString:string];
        NSCharacterSet *numbers;
        NSRange         pointRange = [textField.text rangeOfString:@"."];
        
        if ((pointRange.length > 0) && (pointRange.location < range.location  || pointRange.location > range.location + range.length)) {
            numbers = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
        } else {
            numbers = [NSCharacterSet characterSetWithCharactersInString:@"0123456789."];
        }
        
        if ([textField.text isEqualToString:@""] && [string isEqualToString:@"."] ) {
            return NO;
        }
        
        short remain = 2; //默認(rèn)保留2位小數(shù)
        
        NSString *tempStr = [textField.text stringByAppendingString:string];  // 原來的字符+當(dāng)前輸入的字符
        NSUInteger strlen = [tempStr length];
        if(pointRange.length > 0 && pointRange.location > 0) { //判斷輸入框內(nèi)是否含有“.”。
            if([string isEqualToString:@"."]) { //當(dāng)輸入框內(nèi)已經(jīng)含有“.”時，如果再輸入“.”則被視為無效。
                return NO;
            }
            if(strlen > 0 && (strlen - pointRange.location) > remain+1) { //當(dāng)輸入框內(nèi)已經(jīng)含有“.”，當(dāng)字符串長度減去小數(shù)點前面的字符串長度大于需要要保留的小數(shù)點位數(shù)，則視當(dāng)次輸入無效。
                return NO;
            }
        }
        
        NSRange zeroRange = [textField.text rangeOfString:@"0"];
        if(zeroRange.length == 1 && zeroRange.location == 0){ //判斷輸入框第一個字符是否為“0”
            if(![string isEqualToString:@"0"] && ![string isEqualToString:@"."] && [textField.text length] == 1){ //當(dāng)輸入框只有一個字符并且字符為“0”時，再輸入不為“0”或者“.”的字符時，則將此輸入替換輸入框的這唯一字符。
                textField.text = string;
                return NO;
            }else{
                if(pointRange.length == 0 && pointRange.location > 0){ //當(dāng)輸入框第一個字符為“0”時，并且沒有“.”字符時，如果當(dāng)此輸入的字符為“0”，則視當(dāng)此輸入無效。
                    if([string isEqualToString:@"0"]){
                        return NO;
                    }
                }
            }
        }
        
        NSString *buffer;
        if ( ![scanner scanCharactersFromSet:numbers intoString:&buffer] && ([string length] != 0) )
        {
            return NO;
        }
        // 大于10億的時候不能再編輯
        if ([tempStr longLongValue] >= 1000000000) {
            return NO;
        }
    }
    return YES;
}

- (void)textfieldEditingDidBegin:(UITextField *)textField
{
    if ([textField.text containsString:@"元"]) {
        textField.text = [textField.text stringByReplacingOccurrencesOfString:@"元" withString:@""];
    }
    if ([textField.text containsString:@","]) {
        textField.text = [textField.text stringByReplacingOccurrencesOfString:@"," withString:@""];
    }
}

- (void)textfieldEditingDidEnd:(UITextField *)textField
{
    textField.text = [NSString stringWithFormat:@"%@元", [NSString balanceFormatFromStr:[NSString stringWithFormat:@"%.2f", [textField.text doubleValue]]]];
}

用到的NSString的分類

/**
 *  格式化每三位帶逗號的數(shù)據(jù)
 *  @param string 余額數(shù)據(jù)字符串
 *  @return 帶逗號余額
 */
+ (NSString *)balanceFormatFromStr:(NSString*)string
{

    NSNumberFormatter *numFormatter = [[NSNumberFormatter alloc] init];
    [numFormatter setNumberStyle:NSNumberFormatterCurrencyStyle];
    NSNumberFormatter *numFormatter2 = [[NSNumberFormatter alloc] init];
    [numFormatter2 setNumberStyle:NSNumberFormatterNoStyle];
    NSNumber *num = [numFormatter2 numberFromString:string];
    NSString *tempStr = [numFormatter stringFromNumber:num];
    NSString *balanceStr = [tempStr substringFromIndex:1];
    if ([tempStr hasPrefix:@"-"]) {
        balanceStr = [NSString stringWithFormat:@"-%@",[tempStr substringFromIndex:2]];
    }
    return balanceStr;
    
}