How to reconnect the socket from the background to the foreground on iOS

After a few years of iOS development, there is really no better time to recommend that you add a gesture to unlock the page about the 5min limit, you can put a timestamp in the applicationdidenterbackground method, and then judge the time next time you go to the foreground.

Put accept() outside of while(), and then create two threads inside while(), send and recv. If you make a mistake, you should only create two threads in the main function, while(1) is put in the thread, and send and recv are put in while(1).

1. A VoIP application needs to have the following requirements:

1. Add the UIbackgroundModes key and set the value to VOIP;

3. Before the app is switched to the background, you need to call the setkeepalivetimeout:handler: method to register a handler that executes periodically to keep the app connected to the server;

4. Configure an audio session.

2. The VoIP value of the UIbackgroundModes key has three functions:

3. Configure the keep-alive handler

A VoIP app needs to be woken up periodically to prevent losing connection to the server. To achieve this, the iOS system allows us to use SetKeepAliveTimeOut:Handler:

methods to achieve the keep-alive. Usually we need to implement the keepalive method after the software is cut to the background, that is, in applicationdidenterbackground:.

After the Handler is configured, the system will wake up the app in the suspended state before the time out time expires as needed, and the methods in the Handler will be called at least once.

1、 handler

It should be noted that this handler needs to be returned as quickly as possible when executed in the background, because the system only gives a maximum of 10 seconds to execute it. If the execution is not completed within 10 seconds, and there is no additional execution time, the system will suspend the app.

2、timeout

When you set a handler, you need to specify the maximum timeout period required by the app. The minimum value allowed by the iOS system is 600s, and if you want to set a small dot value, the Handler setting will fail. When the system executes the handler content, it only guarantees that the timeout time will be executed before the timeout, but does not guarantee the accurate execution time, and the system will determine a suitable time point according to the system conditions such as the task situation at that time, which has achieved the purpose of extending the battery life.

The external access interface provided by the server side of iOS. You can't use a session session to save a user's login state like web server development. Therefore, for the security of interface access, do some security authentication on the server side before requesting the interface to return data.

There are some solutions, such as using or customizing some access policies, some as you said using tokens, and some are to send the user's information to the server through the request header httpheader when making a request. It's okay to do it all ways.

Provider refers to the push server of an iPhone software, APNS is the abbreviation of Apple Push Notification Service, which is Apple's server.

The diagram above can be divided into three phases:

Stage 1: The application packages the message to be sent and the identity of the destination iPhone and sends it to APNS.

Stage 2: APNS looks for the iPhone with the corresponding logo in its own list of iPhones that have registered for the Push service, and sends a message to the iPhone.

Stage 3: The iPhone delivers the message to the corresponding application, and pops up a push notification according to the setting.