iOS TextField 针对中文键盘限制输入字符串长度

对 textField 添加监测事件

[self.nameTextField addTarget:self action:@selector(textFieldValueChange:) forControlEvents:UIControlEventEditingChanged];

实现监测事件

 NSInteger kMaxLength =16;
    NSString*toBeString = textField.text;
    NSString *lang = [[UIApplication sharedApplication]textInputMode].primaryLanguage;
    if([lang isEqualToString:@"zh-Hans"]) {
        UITextRange*selectedRange = [textField markedTextRange];
        //获取高亮部分
        UITextPosition*position = [textField positionFromPosition:selectedRange.start offset:0];
        if (!position) {// 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(toBeString.length> kMaxLength) {
                textField.text= [toBeString substringToIndex:kMaxLength];
            }
        }else{//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
        if(toBeString.length> kMaxLength) {
            textField.text= [toBeString substringToIndex:kMaxLength];
        }
    }