限制UITextField输入(解决末尾汉字无法键入问题)

#define kMaxLength 10

[self.searchText addTarget:self action:@selector(textChanged:) forControlEvents:UIControlEventEditingChanged];

- (void)textChange:(UITextField *)textField{
  //限制输入字符数
    NSString *toBeString = textField.text;
    NSString *lang = [textField.textInputMode primaryLanguage]; // 键盘输入模式
    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 > kMaxLength) {
                textField.text = [toBeString substringToIndex:kMaxLength];
            }
        }
        //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 > kMaxLength) {
            textField.text= [toBeString substringToIndex:kMaxLength];
        }
    }
}