Tips for using textviewdidchange of uitextview

UItextview Use in projects ：
This control is generally used in projects , To achieve the following effects . Now let's realize .

stay .h In the document

{
    UITextView *tvRemark; //  Feedback content 
    UILabel *labNumber; //  Number of words 
}

stay .m In the document

- (void)viewDidLoad {
//  Input content 
      UIView *viewRemark = [[UIView alloc] init];
     viewRemark.backgroundColor = [UIColor whiteColor];
    [self.view addSubview:viewRemark];
    
    UILabel *labRemark = [[UILabel alloc] init];
    labRemark.text = @" Feedback content ";
    labRemark.font = [UIFont systemFontOfSize:15];
    labRemark.textColor = [UIColor blackColor];
    [viewRemark addSubview:labRemark];
    
    UILabel *labTag = [[UILabel alloc] init];
    labTag.textColor = [UIColor redColor];
    labTag.text = @"*";
    [viewRemark addSubview:labTag];
    
    tvRemark = [[UITextView alloc] init];
    tvRemark.font = [UIFont systemFontOfSize:13];
    tvRemark.delegate = self;
    [viewRemark addSubview:tvRemark];
    // _placeholderLabel
    UILabel *placeHolderLabel = [[UILabel alloc] init];
    placeHolderLabel.text = @" Please fill in 10 More than words of problem description , So that we can better help you solve the problem ";
    placeHolderLabel.numberOfLines = 0;
    placeHolderLabel.textColor = [UIColor lightGrayColor];
    [placeHolderLabel sizeToFit];
    placeHolderLabel.font = [UIFont systemFontOfSize:13.f];
    [tvRemark addSubview:placeHolderLabel];
    [tvRemark setValue:placeHolderLabel forKey:@"_placeholderLabel"];
    labNumber = [[UILabel alloc] init];
    labNumber.textColor = [UIColor lightTextColor];
    labNumber.font = [UIFont systemFontOfSize:13];
    labNumber.text = @"0/200";
    [viewRemark addSubview:labNumber];
    
    //  What is used below is Masonry A third party  SDK The layout of the controls 
    [viewRemark mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.mas_equalTo(viewPic.mas_bottom).offset(10);
        make.height.mas_equalTo(168);
        make.width.mas_equalTo(SCREEN_WIDTH);
    }];
    
    [labRemark mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.mas_equalTo(15);
        make.top.mas_equalTo(viewRemark.mas_top).offset(8);
        make.height.mas_equalTo(20);
    }];
    
    [labTag mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.mas_equalTo(labRemark.mas_right).offset(5);
        make.top.bottom.mas_equalTo(labRemark);
    }];
    
    [tvRemark mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.mas_equalTo(15);
        make.right.mas_equalTo(-15);
        make.top.mas_equalTo(labRemark.mas_bottom).offset(8);
        make.height.mas_equalTo(100);
    }];
    [labNumber mas_makeConstraints:^(MASConstraintMaker *make) {
        make.right.mas_equalTo(-15);
        make.top.mas_equalTo(tvRemark.mas_bottom).offset(8);
        make.height.mas_equalTo(15);
        make.bottom.mas_equalTo(viewRemark.mas_bottom).offset(-20);
    }];
}

The following code is more important , The method is textview Of UITextViewDelegate. Is to control the change of the number of input words .

stay .m In the document

-(void)textViewDidChange:(UITextView *)textView{
    NSString *lang = textView.textInputMode.primaryLanguage; //  Keyboard input mode 

        if ([lang isEqualToString:@"zh-Hans"]){

            UITextRange *selectedRange = [textView markedTextRange];

            if (!selectedRange) { //  No highlight 

                if (textView.text.length>200) { //  The input text is longer than the set length    The setting here is 200 Characters 
                    tvRemark.text = [textView.text substringToIndex:200];
                }else{
                    tvRemark.text = textView.text;
                }
                labNumber.text = [NSString stringWithFormat:@"%lu/200",(unsigned long)textView.text.length];

            }else{
            }
        }else{
            if (textView.text.length>200) {
                tvRemark.text = [textView.text substringToIndex:200];
            }else{
                tvRemark.text = textView.text;
            }
            labNumber.text = [NSString stringWithFormat:@"%lu/200",(unsigned long)textView.text.length];
        }
}

tvRemark Is initialized UItextview; labNumber Is to display the input text UIlabel Control . among

[lang isEqualToString:@"zh-Hans"]   This sentence is to judge whether it is Chinese , Prevent English synchronization from being counted .
selectedRange   Judge TextView Whether it is in the highlighted state .
textView.text.length  Indicates the number of text currently entered .

In later use , Colleagues found problems . Use the above -(void)textViewDidChange:(UITextView *)textView There will be a problem of jumping directly to the end after entering a sentence in the middle . So it was modified . as follows :

-(void)textViewDidChange:(UITextView *)textView{
    
    NSString *lang = textView.textInputMode.primaryLanguage;// Keyboard input mode 

        if ([lang isEqualToString:@"zh-Hans"]){
    

            UITextRange *selectedRange = [textView markedTextRange];

            if (!selectedRange) {
    // Marked text 

                if (textView.text.length>200) {
    
                    self.tvRemark.text = [textView.text substringToIndex:200];
                }
            }
        }else{
    

            if (textView.text.length>200) {
    
                self.tvRemark.text = [textView.text substringToIndex:200];
            }
        }
            
    self.labNumber.text = [NSString stringWithFormat:@"%lu/200",(unsigned long)self.tvRemark.text.length];
            
    if (_delegate && [_delegate respondsToSelector:@selector(CtextViewTextChange:)]) {
    
         [self.delegate CtextViewTextChange:self.tvRemark.text];
    }
}

Through the above code, we can realize UItextview Common page status . If the above code is used in multiple places , It is recommended to create a new class , Manage the code in a unified way .