（一）APP應(yīng)用有以下幾種狀態(tài)：
Not running：應(yīng)用未運(yùn)行；
InActive：應(yīng)用在前臺(tái)未活動(dòng)兔朦；
Active:應(yīng)用處于活動(dòng)狀態(tài)；
Background：運(yùn)行在background和正在執(zhí)行代碼；
suspend：運(yùn)行在background和未執(zhí)行代碼匀泊；
當(dāng)應(yīng)用啟動(dòng)時(shí)：
由not running-(1)->InActive-(2)->Active.
(1):調(diào)用application:didFinishLaunchingWithOptions
(2):調(diào)用applicationDidBecomeActive
當(dāng)應(yīng)用切換APP時(shí)：
由Active-(1)->InActive-(2)->running。
(1):調(diào)用applicationWillResignActive
(2):調(diào)用applicationDidEnterBackground
切換回來時(shí)
由running-(1)->InActive-(2)->Active
(1):調(diào)用applicationWillEnterForeground
(2):調(diào)用applicationDidBecomeActive
（二）ViewController生命周期
alloc-->init-->loadView-->viewDidLoad-->viewWillAppear-->viewDidAppear
Viewcontroller被銷毀時(shí)：
viewWillDisappear-->viewDidDisappear-->dealloc
