iOS 解决汉字联想输入，导致字数限制失效的问题

- (void)viewDidLoad {
       [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textViewEditChanged:) name:UITextFieldTextDidChangeNotification object:detailAddress];      
}

// 监听文本改变
-(void)textViewEditChanged:(NSNotification *)obj{
    
    UITextField *textField = (UITextField *)obj.object;

    NSString *toBeString = textField.text;
    
    NSString *lang = [[UITextInputMode currentInputMode] primaryLanguage]; // 键盘输入模式
    
    NSUInteger maxLength = MaxNumberOfDescriptionChars-curZone.text.length-1;//加上自动定位的地址，上限是45个汉字
    
    if ([lang isEqualToString:@"zh-Hans"]) { // 简体中文输入，包括简体拼音，健体五笔，简体手写
        
        UITextRange *selectedRange = [textField markedTextRange];
        
        //获取高亮部分
        
        UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0];
        
        // 没有高亮选择的字，则对已输入的文字进行字数统计和限制
        
        if (!position) {
            
            if (toBeString.length > maxLength) {
                
                textField.text = [toBeString substringToIndex:maxLength];
                
            }
            
        }
        
        // 有高亮选择的字符串，则暂不对文字进行统计和限制
        
        else{
            
            
            
        }
        
    }
    
    // 中文输入法以外的直接对其统计限制即可，不考虑其他语种情况
    
    else{
        
        if (toBeString.length > maxLength) {
            
            textField.text = [toBeString substringToIndex:maxLength];
            
        }
        
    }
    
}

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    
    if ([string isEqualToString:@""])
    {
        return YES;
    }
    NSString * toBeString = [textField.text stringByReplacingCharactersInRange:range withString:string];
    
    if (detailAddress == textField)
    {
        NSUInteger maxLength = MaxNumberOfDescriptionChars;//设置文字上限
        if ([toBeString length] > maxLength) {
            textField.text = [toBeString substringToIndex:maxLength];
            [Utils showToastWithText:@"超过最大字数限制"];
            return NO;
        }
    }
    return YES;
}