iOS开发小技巧--即时通讯项目:使用富文本在UILabel中显示图片和文字;使用富文本占位显示图片

Label借助富文本显示图片

1.即时通讯项目中语音消息UI的实现,样式如图:

• 借助富文本在UILabel中显示图片和文字

// 1.创建一个可变的富文本
    NSMutableAttributedString *voiceAttr = [[NSMutableAttributedString alloc] init];
    if ([self.reuseIdentifier isEqualToString:@"receiveCell"]) { // 接收方的label:图片 + 时间

        // 2.创建图片富文本附件
        NSTextAttachment *imageAttachment = [[NSTextAttachment alloc] init];
        UIImage *voiceImage = [UIImage imageNamed:@"chat_receiver_audio_playing_full"];
        // 2.1指定富文本附件的图片
        imageAttachment.image = voiceImage;
        // 2.2设置图片的frame,-7是为了图片和文字横向对齐一点
        imageAttachment.bounds = CGRectMake(0, -7, 30, 30);
        // 2.3将图片富文本附件添加到富文本中
        NSAttributedString *imgAttr = [NSAttributedString attributedStringWithAttachment:imageAttachment];
        // 3.将图片富文本添加到可变的富文本中
        [voiceAttr appendAttributedString:imgAttr];
        // 4.创建时间文字的富文本
        EMVoiceMessageBody *voiceBody = [message.messageBodies firstObject];
        NSInteger time = voiceBody.duration;
        NSAttributedString *timeAtt = [[NSAttributedString alloc] initWithString:[NSString stringWithFormat:@"      %ld″",time]];
        [voiceAttr appendAttributedString:timeAtt];
    } else { // 发送方的label: 时间 + 图片

        // 4.创建时间文字的富文本
        EMVoiceMessageBody *voiceBody = [message.messageBodies firstObject];
        NSInteger time = voiceBody.duration;
        NSAttributedString *timeAtt = [[NSAttributedString alloc] initWithString:[NSString stringWithFormat:@"%ld″      ",time]];
        [voiceAttr appendAttributedString:timeAtt];
        // 2.创建图片富文本
        NSTextAttachment *imageAttachment = [[NSTextAttachment alloc] init];
        UIImage *voiceImage = [UIImage imageNamed:@"chat_sender_audio_playing_full"];
        imageAttachment.image = voiceImage;
        imageAttachment.bounds = CGRectMake(self.msgLabel.bounds.size.width - 30, -7, 30, 30);
        NSAttributedString *imgAttr = [NSAttributedString attributedStringWithAttachment:imageAttachment];
        // 3.将图片富文本添加到可变的富文本中
        [voiceAttr appendAttributedString:imgAttr];
    }

2.即时通讯发送图片 -- 在UILabel中添加了UIImageView,虽然设置了UILabel的尺寸,但是并没有什么卵用.UILabel尺寸没变,图片也显示的不全

• 使用富文本当做占位符的作用,先将UILabel撑到显示图片的大小
• 最后将UIImageView添加到UILabel中问题就解决了

EMImageMessageBody *imageBody = [self.message.messageBodies firstObject];

    // 1.给label设置富文本,目的:占位,将label撑大,足够显示缩略图
    NSTextAttachment *attachment = [[NSTextAttachment alloc] init];
    attachment.bounds = (CGRect){0, 0, imageBody.thumbnailSize};
    // 2.给label添加富文本
    self.msgLabel.attributedText = [NSAttributedString attributedStringWithAttachment:attachment];

    // 3.将UIImageView添加到UILabel中
    [self.msgLabel addSubview:self.msgImageView];
    NSString *path;

    NSFileManager *manager = [NSFileManager defaultManager];
    if ([manager fileExistsAtPath:[imageBody thumbnailLocalPath]]) { // 本地有图片的情况

        path = imageBody.thumbnailLocalPath;

        [self.msgImageView sd_setImageWithURL:[NSURL fileURLWithPath:path] placeholderImage:nil];
    } else { // 本地没有图片的情况
        path = imageBody.thumbnailRemotePath;

        [self.msgImageView sd_setImageWithURL:[NSURL URLWithString:path] placeholderImage:nil];
    }
    // 4.设置图片的位置与尺寸
    self.msgImageView.frame = (CGRect){0, 0, imageBody.thumbnailSize};