iOS远程推送的实现

远程推送是指服务端给客户端发送消息时，客户端能接收并且如果程序处于后台状态时还能弹出推送窗口，即使程序不在后台运行时也能进行推送，像微信、QQ那样。

要实现远程推送，需要以下步骤:

1.在工程项目的capabilites将Push Notifications打开，此时会在项目中生成一个entitlements文件

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2.在appdelegate中申请推送权限

//iOS10及以上系统申请方式
UNUserNotificationCenter *center = [UNUserNotificationCenter currentNotificationCenter];
//必须写代理，不然无法监听通知的接收与点击事件
center.delegate = self;
[center requestAuthorizationWithOptions:(UNAuthorizationOptionBadge | UNAuthorizationOptionSound | UNAuthorizationOptionAlert) completionHandler:^(BOOL granted, NSError * _Nullable error) {
    if (!error && granted) {
        NSLog(@"用户点击允许，注册成功");
    }else {
        NSLog(@"用户点击不允许，注册失败");
    }
}];

 //iOS8到iOS10系统申请方式
UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:UIUserNotificationTypeAlert | UIUserNotificationTypeBadge | UIUserNotificationTypeSound categories:nil];
[application registerUserNotificationSettings:settings];

3.在appdelegate中添加代码，以获取device token

- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken{

NSString *deviceString = [[deviceToken description] stringByTrimmingCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@"<>"]];
deviceString = [deviceString stringByReplacingOccurrencesOfString:@" " withString:@""];

NSLog(@"deviceToken===========%@",deviceString);
}

//在这里接收远程推送的信息
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler {
NSLog(@"iOS7及以上系统，收到通知:%@", userInfo);
completionHandler(UIBackgroundFetchResultNewData);

}

4..申请一个push证书

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5.准备完毕，开始模拟远程推送，下载第三方工具pusher,在钥匙串中将push证书导出p12文件，在pusher工具中导入，并且添加刚刚获取的device token，文本框内为push内容，可以直接使用进行测试，点击push，即可在手机端看到实现效果，注意，需要在真机上进行测试。

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