記錄一下限制輸入字符的判斷。不僅局限于中文或英文

• 首先在ViewDidLoad中注冊通知

[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(textFieldEditChanged:)
    name:@"UITextFieldTextDidChangeNotification" object:self.userTF];

• 下面是判斷邏輯 由于需求有中文鍵盤下的字母數字輸入，所以其中那部分判斷如不需要可以去除

// 輸入字符判斷
-(void)textFieldEditChanged:(NSNotification *)obj {
    UITextField *textField = (UITextField *)obj.object;
    NSString *toBeString = textField.text;
    NSString *lang = [textField.textInputMode primaryLanguage];
    if ([lang isEqualToString:@"zh-Hans"])// 簡體中文輸入
        {
        //獲取高亮部分
        UITextRange *selectedRange = [textField markedTextRange];
        UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0];
     
        // 沒有高亮選擇的字，則對已輸入的文字進行字數統計和限制
        
        if (!position || !selectedRange)
        {
            if (toBeString.length > MAX_CHINESE_LENGTH)
            {
                NSRange rangeIndex = [toBeString rangeOfComposedCharacterSequenceAtIndex:MAX_CHINESE_LENGTH];
                if (rangeIndex.length == 1)
                {
                    
                    textField.text = [toBeString substringToIndex:MAX_CHINESE_LENGTH];
                }
                else
                {
                    NSRange rangeRange = [toBeString rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, MAX_CHINESE_LENGTH)];
                    textField.text = [toBeString substringWithRange:rangeRange];
                }
            }
            if (toBeString.length > MAX_ENGLISH_LENGTH)
            {
                NSRange rangeIndex = [toBeString rangeOfComposedCharacterSequenceAtIndex:MAX_ENGLISH_LENGTH];
                if (rangeIndex.length == 1)
                {
                    textField.text = [toBeString substringToIndex:MAX_ENGLISH_LENGTH];
                }
                else
                {
                    NSRange rangeRange = [toBeString rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, MAX_ENGLISH_LENGTH)];
                    textField.text = [toBeString substringWithRange:rangeRange];
                }
            }
        } 
    }
        // 中文輸入法以外的直接對其統計限制即可，不考慮其他語種情況
        else
        {
            if (toBeString.length > MAX_ENGLISH_LENGTH)
                {
                    NSRange rangeIndex = [toBeString rangeOfComposedCharacterSequenceAtIndex:MAX_ENGLISH_LENGTH];
                    if (rangeIndex.length == 1)
                    {
                        textField.text = [toBeString substringToIndex:MAX_ENGLISH_LENGTH];
                    }
                    else
                    {
                NSRange rangeRange = [toBeString rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, MAX_ENGLISH_LENGTH)];
                textField.text = [toBeString substringWithRange:rangeRange];
                    }
                }
            }
        } 

附上我的博客鏈接：oragekk'Blog 歡迎留言-不過評論系統換成了disqus需要搭梯子哦