加载gif图片

NSImage *img = [NSImage imageNamed:@"earth.gif"]; // or similar
//    [self.window.contentView setWantsLayer:YES];
    _imageView.imageScaling = NSImageScaleNone;
    _imageView.animates = YES;
    _imageView.image = img;
    _imageView.canDrawSubviewsIntoLayer = YES;
    [_imageView setImage:img];