#pragma mark - UITextField Delegate 
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    // 判斷是否已經(jīng)存在小數(shù)點(diǎn)
    if ([string isEqualToString:@"."] && [textField.text stringByReplacingOccurrencesOfString:@" " withString:@""].length == 0) {
        textField.text = @"";
        return NO;
    } else if ([string isEqualToString:@"."] && [textField.text containsString:@"."]) {
        return NO;
    }
 
    NSMutableString * futureString = [NSMutableString stringWithString:textField.text];
    [futureString  insertString:string atIndex:range.location];
    NSInteger flag=0;
    const NSInteger limited = 2;  // 小數(shù)點(diǎn)  限制輸入兩位
    for (NSInteger i = futureString.length-1; i>=0; i--) {
        if ([futureString characterAtIndex:i] == '.') {
            if (flag > limited)   return NO;
            break;
        }
        flag++;
    }
    return YES;
}

使用category 方式處理 限制輸入框輸入標(biāo)點(diǎn)符號(hào)后保留后兩位

給輸入添加監(jiān)聽(tīng)付費(fèi)
 [self.priceField addTarget:self action:@selector(textFieldEditingChanged:) forControlEvents:UIControlEventEditingChanged];


--------調(diào)用以下 UITextField 中添加的類別方法 
/**
 *
 *  輸入框限制輸入處理保留兩位小數(shù)點(diǎn)方法
 */
- (void)moneyTFDidTextChanged:(NSInteger)numEnob{
    
    if([self.text hasPrefix:@"0"] && self.text.length == 2){//如果用戶第一輸入了0粘昨，那么就不能讓用戶繼續(xù)輸入0~9的數(shù)字了
        NSString *subString = [self.text substringFromIndex:1];
        if (([subString integerValue] >0 && [subString integerValue] <= 9) || [subString isEqualToString:@"0"]) {
            self.text = [self.text substringToIndex:1];
        }
    }else if (self.text.length > numEnob && ![self.text containsString:@"."]){  //如果輸入不為'.',則限制輸入6位數(shù)
        self.text = [self.text substringToIndex:numEnob];
    }
    
    if ([self.text containsString:@"."]) {//如果輸入的文本中含有小數(shù)點(diǎn),則進(jìn)入該方法
        NSRange range = [self.text rangeOfString:@"."];
        
        if (range.location == 0) {//如果小數(shù)點(diǎn)位置是第一位，則默認(rèn)為0.
            self.text = @"0.";
        }else{//說(shuō)明小數(shù)點(diǎn)的位置不是第一位
            if (self.text.length > 2) {
                NSString *subString = [self.text substringFromIndex:range.location + 1];//取出小數(shù)點(diǎn)后面的字符串
                subString = [subString stringByReplacingOccurrencesOfString:@"." withString:@""]; //將用戶多輸入的'.'去除
                if (subString.length > 2) {//小數(shù)點(diǎn)后面保留2位
                    subString = [subString substringToIndex:2];
                }
                if ([self.text hasPrefix:@"0."]) {
                    self.text = [NSString stringWithFormat:@"0.%@",subString];
                }else{
                    NSString *subString1 = [self.text substringToIndex:range.location];
                    self.text = [NSString stringWithFormat:@"%@.%@",subString1,subString];//拼接新的字符串
                }
            }
        }
    }
}

輸入框只能輸入數(shù)字和小數(shù)點(diǎn)后保留幾位的方法

//輸入框中只能輸入數(shù)字和小數(shù)點(diǎn)，且小數(shù)點(diǎn)只能輸入一位，參數(shù)number 可以設(shè)置小數(shù)的位數(shù)调窍，該函數(shù)在-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string調(diào)用；

-(BOOL)isValidAboutInputText:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string decimalNumber:(NSInteger)number{
    
    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 = number; //保留 number位小數(shù)
    NSString *tempStr = [textField.text stringByAppendingString:string];
    NSUInteger strlen = [tempStr length];
    if(pointRange.length > 0 && pointRange.location > 0){ //判斷輸入框內(nèi)是否含有“.”乏悄。
        if([string isEqualToString:@"."]){ //當(dāng)輸入框內(nèi)已經(jīng)含有“.”時(shí)氮凝，如果再輸入“.”則被視為無(wú)效。
            return NO;
        }
        if(strlen > 0 && (strlen - pointRange.location) > remain+1){ //當(dāng)輸入框內(nèi)已經(jīng)含有“.”萝映，當(dāng)字符串長(zhǎng)度減去小數(shù)點(diǎn)前面的字符串長(zhǎng)度大于需要要保留的小數(shù)點(diǎn)位數(shù)吴叶，則視當(dāng)次輸入無(wú)效。
            return NO;
        }
    }
    NSRange zeroRange = [textField.text rangeOfString:@"0"];
    if(zeroRange.length == 1 && zeroRange.location == 0){ //判斷輸入框第一個(gè)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(gè)字符并且字符為“0”時(shí)序臂，再輸入不為“0”或者“.”的字符時(shí)蚌卤，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(gè)字符為“0”時(shí)奥秆，并且沒(méi)有“.”字符時(shí)逊彭，如果當(dāng)此輸入的字符為“0”，則視當(dāng)此輸入無(wú)效构订。
                if([string isEqualToString:@"0"]){
                    return NO;
                }
            }
        }
    }
    NSString *buffer;
    if ( ![scanner scanCharactersFromSet:numbers intoString:&buffer] && ([string length] != 0) ){
        return NO;
    }else{
        return YES;
    }
}