[WXApi registerApp:weixinAppKey];

if(![WXApi isWXAppInstalled]){
        UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"信息" message:@"未安装微信，不能分享" delegate:nil cancelButtonTitle:@"我知道了" otherButtonTitles:nil];
        [alert show];
        return;
    }
    if(![WXApi isWXAppSupportApi]){
        UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"信息" message:@"微信不支持该API" delegate:nil cancelButtonTitle:@"我知道了" otherButtonTitles:nil];
        [alert show];
        return;
    }
    
    WXMediaMessage *message = [WXMediaMessage message];
    [message setThumbImage:[UIImage imageNamed:@"logo.png"]];
    NSString  *str=@"";
    message.title=str;
    message.description=str;
    

//链接
    WXWebpageObject *webObj = [WXWebpageObject object];
    webObj.webpageUrl = downloadURL;
    message.mediaObject = webObj;
//图片 
//    WXImageObject *imageObject = [WXImageObject object];
//    UIImage *image = [UIImage imageNamed:@"install.png"];
//    imageObject.imageData = UIImagePNGRepresentation(image);
//    message.mediaObject = imageObject;
    
    SendMessageToWXReq* request = [[SendMessageToWXReq alloc] init];
    
    request.bText = NO;
    request.message = message;
    request.scene = WXSceneTimeline;
    [WXApi sendReq:request];
通过以上分享于朋友圈或朋友时，隐藏了一个小问题并且微信api包不提供错误信息，即[message setThumbImage:[UIImage imageNamed:@"logo.png"]]，当缩略图过大，将分享不成功，即无法打开微信客户端

解决办法：换图，改变缩略图大小

ios 分享微信