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:0 error:nil];
    }
    //通过正则表达式识别出emojiText
    NSArray *matches = [regExpress matchesInString:content options:0 range:NSMakeRange(0, content.length)];
    if(matches.count > 0){
        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==0){
        return nil;
    }
    NSString *imageName = _emojiDic[emojiText];
    if(imageName.length == 0){
        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(0, 0, 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(0, -3, 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>0){
        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, 0);
}

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>0){
        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>0){
        [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:10];
    NSRange effectiveRange = NSMakeRange(range.location,0);
    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;
}