iOS background mechanism

Recently in the module on the preservation of the interface information, access to relevant information, the background mechanism of iOS has a systematic understanding, now summed up:

iOS is "pseudo-backstage",so-called "back-Office" in iOS does not refer to "executing programs", but "Recently used programs".

Close--------This program to completely shut down or has not been opened

The pending--------program is turned on, but no instructions are received (e.g., the program is turned on but the user has locked the machine)

Programs in use----normal use

Background--------Program is not open but still running code in the background

Pause--------Program is still using memory but not running code, the program only has 5 seconds of processing time after shutting down

In fact, you do not need to manage the multi-task background of IOS, because you see in the background of the program is not really running, in fact, multi-task background is not the actual task manager, more precisely, more like a browser-like history of things, but specifically for the program's record only. in general, multitasking is just a tool that allows users to switch between recently opened programs, and the best proof of this is that when you restart your iphone, all your recently opened programs are displayed in the multi-tasking background, and obviously they can't be running. So when you press the home key to leave the program, you do not need to go to the multi-task backstage, because 90% of the program will stop when you press the home key to leave the program.

Technically, all Cheng have a 5-second background time when they press the home button, and iOS gives them a very limited amount of time to clear what they need to clear before they turn them into a paused state, and then the program remains Memory so that it can be opened quickly. Special needs program can reach 10 minutes 。