iOS开发之TextField钱以及小数点的实时限制输入

钱的限制输入条件

1.可以输入小数点后N位

2.第一位是0,第二位不能是0

3.不能以.开始

方法一

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString*)string
{
    NSCharacterSet *characterSet;
    NSUInteger dotLocation = [textField.text rangeOfString:@"."].location;
    
    if ([textField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]].length == 0 && [string isEqualToString:@"."]) {
        textField.text = @"0.";
        return NO;
    }
    if (dotLocation == NSNotFound && range.location != 0) {
        NSMutableCharacterSet *mutableCharacterSet = [NSMutableCharacterSet decimalDigitCharacterSet];
        [mutableCharacterSet addCharactersInString:@"."];
        characterSet = [mutableCharacterSet invertedSet];
    }else {
        characterSet = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
    }
    
    NSString *filtered = [[string componentsSeparatedByCharactersInSet:characterSet] componentsJoinedByString:@""];
    
    BOOL basicTest = [string isEqualToString:filtered];
    
    if(!basicTest) {
        return NO;
    }
    if (dotLocation != NSNotFound && range.location > dotLocation + 2) {
        return NO;
    }
    return YES;
}

方法二

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString*)string
{
   
  NSMutableString * futureString = [NSMutableString stringWithString:textField.text];
  [futureString insertString:string atIndex:range.location];
   
  NSInteger flag=0;
  const NSInteger limited = 1;
  for (int i = futureString.length-1; i>=0; i--) {

    if([futureString characterAtIndex:i] == '.') {
       
      if (flag > limited) {
        return NO;
      }
       
      break;
    }
    flag++;
  }
   
   return YES;
}

方法三

代码忘了在哪看见的了，之前随手收藏的，提供一个思路吧，observeMoney是UITextFiled category中的一个方法

- (void)observeMoney {
    if (!self.isMoney) {
        return;
    }
    NSString *allText = self.text;
    NSString *newText= allText;
    if (self.correctText) {
        NSRange oldTextRange = [allText rangeOfString:self.correctText];
        newText = [allText substringFromIndex:oldTextRange.length];
    }
    
    NSCharacterSet *set = [[NSCharacterSet characterSetWithCharactersInString:@"0123456789."]invertedSet];
    NSString *filtered = [[newText componentsSeparatedByCharactersInSet:set] componentsJoinedByString:@""];
    if (filtered.length == 0) {
        if ([newText isEqualToString:@""]) {//inputed backSpace
            self.correctText = newText;
        }
        self.text = self.correctText;
        return;
    }
    if ([self.correctText rangeOfString:@"."].length) {
        if ([newText isEqualToString:@"."]) {//only one '.'
            self.text = self.correctText;
            return;
        }
        //2 charactors limited after '.'
        NSArray *array =  [self.correctText componentsSeparatedByString:@"."];
        if (array.count == 2) {
            if ([array[1] length] >= 2) {
                NSArray *newStringArray = [newText componentsSeparatedByString:@"."];
                if (newStringArray.count == 2 && [newStringArray[1] length] == 1) {//inputed backSpace
                    self.correctText= newText;
                }
                self.text = self.correctText;
                return;
            }
        }
        
    } else if (self.correctText.length == 1) {
        if ([newText isEqualToString:@"0"] && [self.correctText isEqualToString:@"0"]) {
            self.text = self.correctText;
            return;
        }
    }
    if (self.correctText.length == 0 && [newText isEqualToString:@"."]) {//"."->"0."
        self.text
        = self.correctText
        = @"0.";
        return;
    }
    if (self.correctText.length == 1 && [self.correctText isEqualToString:@"0"]) {
        if (![newText isEqualToString:@"."] && [newText intValue] > 0) {//'0'->other numbers
            self.text
            = self.correctText
            = newText;
            return;
        }
    }
    self.correctText = allText;
}

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