IOS UITextView支持输入、复制、粘贴、剪切自定义表情

UITextView是ios的富文本编辑控件，除了文字还可以插入图片等。今天主要介绍一下UITextView对自定义表情的处理。

1、首先识别出文本中的表情文本，然后在对应的位置插入NSTextAttachment对象，该对象存放的就是自定义表情。

 static NSString *emojiTextPttern = @"\\[[0-9a-zA-Z\\u4e00-\\u9fa5]+\\]";

 _emojiDic = @{@"[大笑]":@"smile",@"[爱心]":@"love"};

 -(NSMutableAttributedString*)getEmojiText:(NSString*)content{
     NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc]initWithString:content attributes:self.typingAttributes];
     static NSRegularExpression *regExpress = nil;
     if(regExpress == nil){
         regExpress = [[NSRegularExpression alloc]initWithPattern:emojiTextPttern options: error:nil];
     }
     //通过正则表达式识别出emojiText
     NSArray *matches = [regExpress matchesInString:content options: range:NSMakeRange(, content.length)];
     if(matches.count > ){
         for(NSTextCheckingResult *result in [matches reverseObjectEnumerator]){
             NSString *emojiText = [content substringWithRange:result.range];
             //构造NSTextAttachment对象
             NSTextAttachment *attachment = [self createEmojiAttachment:emojiText];
             if(attachment){
                 NSAttributedString *rep = [NSAttributedString attributedStringWithAttachment:attachment];
                 //在对应的位置替换
                 [attributedString replaceCharactersInRange:result.range withAttributedString:rep];
             }
         }
     }
     return attributedString;
 }

2、构造NSTextAttachment的过程为：

 -(NSTextAttachment*)createEmojiAttachment:(NSString*)emojiText{
     if(emojiText.length==){
         return nil;
     }
     NSString *imageName = _emojiDic[emojiText];
     if(imageName.length == ){
         return nil;
     }
     UIImage *image = [UIImage imageNamed:imageName];
     if(image == nil){
         return nil;
     }
     //把图片缩放到符合当前textview行高的大小
     CGFloat emojiWHScale = image.size.width/1.0/image.size.height;
     CGSize emojiSize = CGSizeMake(self.font.lineHeight*emojiWHScale, self.font.lineHeight);
     UIImageView *imageView = [[UIImageView alloc]initWithFrame:CGRectMake(, , emojiSize.width, emojiSize.height)];
     imageView.image = image;
     //防止模糊
     UIGraphicsBeginImageContextWithOptions(imageView.bounds.size, NO, [UIScreen mainScreen].scale);
     [imageView.layer renderInContext:UIGraphicsGetCurrentContext()];
     UIImage *emojiImage = UIGraphicsGetImageFromCurrentImageContext();
     UIGraphicsEndImageContext();
     EmojiTextAttachment *attachment = [[EmojiTextAttachment alloc]init];
     attachment.image = emojiImage;
     attachment.emojiText = emojiText;
     attachment.bounds = CGRectMake(, -, emojiImage.size.width, emojiImage.size.height);
     return attachment;
 }

其中EmojiTextAttachment继承了NSTextAttachment类，主要是为了记住自定义表情对应的emojiText，在后面实现copy和cut需要用到。EmojiTextAttachment声明为：

 @interface EmojiTextAttachment : NSTextAttachment

 /**
  保存emojiText的值
  */
 @property (nonatomic, strong) NSString *emojiText;
 @end

3、实现对自定义表情的粘贴

重新paste方法即可

 -(void)paste:(id)sender{
     UIPasteboard *defaultPasteboard = [UIPasteboard generalPasteboard];
     if(defaultPasteboard.string.length>){
         NSRange range = self.selectedRange;
         if(range.location == NSNotFound){
             range.location = self.text.length;
         }
         if([self.delegate textView:self shouldChangeTextInRange:range replacementText:defaultPasteboard.string]){
            NSAttributedString *newAttriString = [self getEmojiText:defaultPasteboard.string];
            [self insertAttriStringToTextview:newAttriString];
         }
         return;
     }
     [super paste:sender];
 }

 -(void)insertAttriStringToTextview:(NSAttributedString*)attriString{
     NSMutableAttributedString *mulAttriString = [[NSMutableAttributedString alloc]initWithAttributedString:self.attributedText];
     NSRange range = self.selectedRange;
     if(range.location == NSNotFound){
         range.location = self.text.length;
     }
     [mulAttriString insertAttributedString:attriString atIndex:range.location];
     self.attributedText = [mulAttriString copy];
     self.selectedRange = NSMakeRange(range.location+attriString.length, );
 }

4、实现自定义表情的拷贝和剪切

拷贝和剪切自定义表情的时候，不是获取自定义表情对应的图片而是自定义表情对应的emojiText，这也是我们在上面要定义EmojiTextAttachment类的原因。具体代码如下：

 -(void)copy:(id)sender{
     NSRange range = self.selectedRange;
     NSString *content = [self getStrContentInRange:range];
     if(content.length>){
         UIPasteboard *defaultPasteboard = [UIPasteboard generalPasteboard];
         [defaultPasteboard setString:content];
         return;
     }
     [super copy:sender];
 }
 -(void)cut:(id)sender{
     NSRange range = self.selectedRange;
     NSString *content = [self getStrContentInRange:range];
     if(content.length>){
         [super cut:sender];
         UIPasteboard *defaultPasteboard = [UIPasteboard generalPasteboard];
         [defaultPasteboard setString:content];
         return;
     }
     [super cut:sender];
 }

 /**
  把textview的attributedText转化为NSString，其中把自定义表情转化为emojiText

  @param range 转化的范围
  @return 返回转化后的字符串
  */
 -(NSString*)getStrContentInRange:(NSRange)range{
     NSMutableString *result = [[NSMutableString alloc]initWithCapacity:];
     NSRange effectiveRange = NSMakeRange(range.location,);
     NSUInteger length = NSMaxRange(range);
     while (NSMaxRange(effectiveRange)<length) {
         NSTextAttachment *attachment = [self.attributedText attribute:NSAttachmentAttributeName atIndex:NSMaxRange(effectiveRange) effectiveRange:&effectiveRange];
         if(attachment){
             if([attachment isKindOfClass:[EmojiTextAttachment class]]){
                 EmojiTextAttachment *emojiAttachment = (EmojiTextAttachment*)attachment;
                 [result appendString:emojiAttachment.emojiText];
             }
         }
         else{
             NSString *subStr = [self.text substringWithRange:effectiveRange];
             [result appendString:subStr];
         }
     }
     return [result copy];
 }

通过上面的努力，我们已经实现了所有的功能。但是我们用起来的时候，会发现两个问题：

1、在自定义表情的后面输入文本，UITextview设置的属性（比如字体大小，颜色等）都消失，又变成了默认属性；

2、在ios 10.11系统上，长按自定义表情的时候，keyboard会退出，并且弹出保存图片的系统窗口，这样的体验也不好。

解决第一个问题：

我们在初始化的时候保存一下UITextview的typingAttributes属性，然后在每次UITextview的内容将要发生变化的时候，重置一下他的该属性。

 @interface ViewController ()<UITextViewDelegate>
 @property (nonatomic, strong)CustomTextView *textView;

 @property (nonatomic, strong)NSDictionary *typingAttributes;
 @end

 -(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{
     textView.typingAttributes = self.typingAttributes;
     return YES;
 }

解决第二个问题：

只需要实现一个delegate方法就行，直接返回NO

 -(BOOL)textView:(UITextView *)textView shouldInteractWithTextAttachment:(NSTextAttachment *)textAttachment inRange:(NSRange)characterRange interaction:(UITextItemInteraction)interaction{
     return NO;
 }