今天介绍一个在程序内分享到微信好友或者朋友圈的例子。
程序内部分享方式一：
点击一个“分享”按钮，弹出一个微信分享界面。点击朋友圈进入“最近聊天好友”选择界面。
Screen Shot 2017-02-27 at 23.22.28.png
点击分享，弹出下图
Screen Shot 2017-02-27 at 23.22.31.png
点击发送给朋友，弹出下图
Screen Shot 2017-02-23 at 10.36.20.png
上述功能是如何实现的呢？请看下面代码
代码1-1
```
NSString *test = @"com.tencent.xin.sharetimeline";
if (![SLComposeViewController isAvailableForServiceType:test]) {
NSLog(@"或者没有配置相关的帐号");
return;
}
// 2.创建分享的控制器
SLComposeViewController *composeVc = [SLComposeViewController composeViewControllerForServiceType:test];
if (composeVc == nil){
NSLog(@"没有安装微信");
return;
}
// 2.1.添加分享的文字
[composeVc setInitialText:@"balabalabala..."];
// 2.2.添加一个图片
[composeVc addImage:[UIImage imageNamed:@"图片名"]];
// 2.3.添加一个链接
[composeVc addURL:[NSURL URLWithString:@"blog.csdn.net/lincsdnnet"]];
// 3.弹出分享控制器（以Modal形式弹出）
[self presentViewController:composeVc animated:YES completion:nil];
// 4.监听用户点击了取消还是发送
/*
SLComposeViewControllerResultCancelled,
SLComposeViewControllerResultDone
*/
composeVc.completionHandler = ^(SLComposeViewControllerResult result){
if (result == SLComposeViewControllerResultCancelled) {
NSLog(@"点击了取消");
} else {
NSLog(@"点击了发送");
}
};
```
上面代码是不是感觉很熟悉，不错上面就是我们常用的Social.Framework
如果你仔细看API，系统只提供了如下几个内部分享类型。
```
SOCIAL_EXTERN NSString *const SLServiceTypeTwitter NS_AVAILABLE(10_8, 6_0);
SOCIAL_EXTERN NSString *const SLServiceTypeFacebook NS_AVAILABLE(10_8, 6_0);
SOCIAL_EXTERN NSString *const SLServiceTypeSinaWeibo NS_AVAILABLE(10_8, 6_0);
SOCIAL_EXTERN NSString *const SLServiceTypeTencentWeibo NS_AVAILABLE(10_9, 7_0);
SOCIAL_EXTERN NSString *const SLServiceTypeLinkedIn NS_AVAILABLE(10_9, NA);
```
仔细看没有提供微信的接口啊？但是上面就是能调用微信分享（如果你安装微信并登陆了）。难道是系统给我们实现了，却没有给我们开放API？但是仔细想想是不是iOS8之后系统推出的Share Extension？如果细看上面弹出微信分享的UI，我们可以确定这就是一个Share Extension。这不是系统实现的微信分享，这是微信App的Share Extension。所以来说这个不是私有API。现在想想苹果封装的Social，真的太棒了。SLComposeViewController能调用所有Share Extension。
下面给大家介绍一个简单获取手机中装的App的所有Share Extension的方法。只需调用下面一句代码。
```
SLComposeViewController *composeVc = [SLComposeViewController composeViewControllerForServiceType:SLServiceTypeSinaWeibo];
```
下面看看控制台输出，手机内所有可用的Share Extension的bundle Id 都出来了。其中 {id =com.up.2.ShareExtension}是我自己写的Share Extension。其他所有字符串(Bundle id)都可以当做[SLComposeViewController composeViewControllerForServiceType:]的参数。
```
2017-02-27 23:59:34.761492 WeixinActivity[6692:2156632] [core] SLComposeViewController initWithServiceType: com.apple.social.sinaweibo
2017-02-27 23:59:34.849563 WeixinActivity[6692:2156679] [core] SLComposeViewController _shareExtensionWithIdentifier: continuous discovery block got extensions (
" {id = com.apple.share.SinaWeibo.post}",
" {id = com.apple.share.TencentWeibo.post}",
" {id = com.taobao.taobao4iphone.ShareExtension}",
" {id = com.tencent.qqmail.shareextension}",
" {id = com.apple.mobilenotes.SharingExtension}",
" {id = com.apple.share.Vimeo.post}",
" {id = com.apple.mobileslideshow.StreamShareService}",
" {id = com.tencent.mqq.ShareExtension}",
" {id = com.tencent.xin.sharetimeline}",
" {id = com.apple.share.Twitter.post}",
" {id = com.apple.share.Flickr.post}",
" {id = com.alipay.iphoneclient.ExtensionSchemeShare}",
" {id = com.apple.Music.MediaSocialShareService}",
" {id = com.apple.share.Facebook.post}",
" {id = com.apple.reminders.RemindersEditorExtension}",
" {id = com.up.2.ShareExtension}",
" {id = com.jianshu.Hugo.Share-Extension}",
" {id = com.apple.Health.HealthShareExtension}"
) error (null)
2017-02-27 23:59:34.853193 WeixinActivity[6692:2156679] [core] SLComposeViewController _shareExtensionWithIdentifier: continuous discovery block did update _identifierToShareExtensionMap {
"com.alipay.iphoneclient.ExtensionSchemeShare" = " {id = com.alipay.iphoneclient.ExtensionSchemeShare}";
"com.apple.Health.HealthShareExtension" = " {id = com.apple.Health.HealthShareExtension}";
"com.apple.Music.MediaSocialShareService" = " {id = com.apple.Music.MediaSocialShareService}";
"com.apple.mobilenotes.SharingExtension" = " {id = com.apple.mobilenotes.SharingExtension}";
"com.apple.mobileslideshow.StreamShareService" = " {id = com.apple.mobileslideshow.StreamShareService}";
"com.apple.reminders.RemindersEditorExtension" = " {id = com.apple.reminders.RemindersEditorExtension}";
"com.apple.share.Facebook.post" = " {id = com.apple.share.Facebook.post}";
"com.apple.share.Flickr.post" = " {id = com.apple.share.Flickr.post}";
"com.apple.share.SinaWeibo.post" = " {id = com.apple.share.SinaWeibo.post}";
"com.apple.share.TencentWeibo.post" = " {id = com.apple.share.TencentWeibo.post}";
"com.apple.share.Twitter.post" = " {id = com.apple.share.Twitter.post}";
"com.apple.share.Vimeo.post" = " {id = com.apple.share.Vimeo.post}";
"com.jianshu.Hugo.Share-Extension" = " {id = com.jianshu.Hugo.Share-Extension}";
"com.taobao.taobao4iphone.ShareExtension" = " {id = com.taobao.taobao4iphone.ShareExtension}";
"com.tencent.mqq.ShareExtension" = " {id = com.tencent.mqq.ShareExtension}";
"com.tencent.qqmail.shareextension" = " {id = com.tencent.qqmail.shareextension}";
"com.tencent.xin.sharetimeline" = " {id = com.tencent.xin.sharetimeline}";
"com.up.2.ShareExtension" = " {id = com.up.2.ShareExtension}";
}
2017-02-27 23:59:34.854222 WeixinActivity[6692:2156632] [core] SLComposeViewController initWithServiceType got extension {id = com.apple.share.SinaWeibo.post} for identifier com.apple.share.SinaWeibo.post
2017-02-27 23:59:34.854439 WeixinActivity[6692:2156632] [core] SLComposeViewController initWithExtension: {id = com.apple.share.SinaWeibo.post} requestedServiceType: com.apple.social.sinaweibo
2017-02-27 23:59:34.867423 WeixinActivity[6692:2156632] [core] SLComposeViewController dealloc
```
当然我们要注意，如果手机没有装微信，你是看不到 " {id =com.tencent.xin.sharetimeline}"。
Tips：如果我没有装微信，但是我强制调用下面代码
代码1-2
```
SLComposeViewController *composeVc = [SLComposeViewController composeViewControllerForServiceType:@"com.tencent.xin.sharetimeline"];
你会看到下面输出
SLComposeViewController initWithServiceType failed to get extension for identifier com.tencent.xin.sharetimeline
2017-02-28 00:08:42.124005 WeixinActivity[6704:2158719] [core] SLComposeViewController dealloc
提示你“failed to get extension”。SLComposeViewController 内部自己释放了，返回nil。如果执行上面的代码1-1，就会发生奔溃。避免奔溃的一个办法就是在调用代码1-2后要判断返回值是不是nil，如果是nil就表示没有装微信，否则后面会奔溃(模态视图控制器为nil)。
Tips：如果手机装有微信，但是没有登录。 调用下面代码
代码1-3
if (![SLComposeViewController isAvailableForServiceType:@"com.tencent.xin.sharetimeline"]) {
NSLog(@"或者没有配置相关的帐号");
return;
}
```
调用代码1-3的时候，如果你已经安装了微信但是微信没有登录则返回NO；在未登录状态下，强制调用微信分享功能，会弹出下面这个界面.
Screen Shot 2017-02-24 at 14.18.14.png
但是如果你没有装微信，这个方法仍然会返回YES。如果想判断有没有安装微信，请调用代码1-2，并检测返回值是否是nil。
程序内部分享方式二：
我们网上经常遇到用UIActivityViewController来实现微信内部分享，这个是可以实现，但是这个实现UI太难定制，而且弹出的界面有很多功能不是我们想要的。而且用UIActivityViewController有一个问题比较棘手，就是弹出的可用分享默认没有微信。我们需要到下面这个界面把微信选上。
代码调用如下：
```
UIActivityViewController *activityView = [[UIActivityViewController alloc] initWithActivityItems:@[@"这里是标题", [UIImage imageNamed:@"Oauth"], [NSURL URLWithString:@"http://www.google.com"]] applicationActivities:activity];
activityView.excludedActivityTypes = @[UIActivityTypeAssignToContact, UIActivityTypeCopyToPasteboard, UIActivityTypePrint];
[self presentViewController:activityView animated:YES completion:nil];
```
Screen Shot 2017-02-24 at 14.18.24.png
然后在UIActivityViewController中才能看到“微信”分享
Screen Shot 2017-02-27 at 23.50.13.png
这种体验在国内app中很少用。
在这篇博客中主要介绍，程序内实现分享的两种方式。
参看上面程序内部分享方式一和程序内部分享方式二。
根据在实际使用程序内部分享方式一中遇到的一些问题，后面推出程序内分享 之二
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