IOS视图控制器的生命周期实例详解

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我是靠谱客的博主有魅力红酒，这篇文章主要介绍IOS视图控制器的生命周期实例详解，现在分享给大家，希望可以做个参考。

IOS视图控制器

所谓的生命周期，也就是几个函数的调用顺序，这里以用Storyboard来创建一个ViewController为例

然后我们测试如下代码

复制代码

// 
// ViewController.m 
// 
// Created by huangwenchen on 14/12/26. 
// Copyright (c) 2014年 huangwenchen. All rights reserved. 
// 
 
#import "ViewController.h" 
 
@interface ViewController () 
 
@end 
 
@implementation ViewController 
 
- (id)initWithCoder:(NSCoder *)aDecoder{ 
  if (self = [super initWithCoder:aDecoder]) { 
    NSLog(@"initWithCoder Called"); 
  } 
  return self; 
} 
- (void)viewDidLoad { 
  [super viewDidLoad]; 
  NSLog(@"viewDidLoad Called"); 
  // Do any additional setup after loading the view, typically from a nib. 
   
} 
- (void)viewWillAppear:(BOOL)animated{ 
  [super viewWillAppear:animated]; 
  NSLog(@"viewWillAppear Called"); 
} 
 
-(void)viewDidAppear:(BOOL)animated{ 
  [super viewDidAppear:animated]; 
  NSLog(@"viewDidAppear Called"); 
 
} 
 
-(void)awakeFromNib{ 
  NSLog(@"awakeFromNib Called"); 
} 
 
-(void)viewWillLayoutSubviews{ 
  NSLog(@"viewWillLayoutSubviews Called"); 
} 
-(void)viewDidLayoutSubviews{ 
  NSLog(@"viewDidLayoutSubviews Called"); 
} 
 
@end

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// 
// ViewController.m 
// 
// Created by huangwenchen on 14/12/26. 
// Copyright (c) 2014年 huangwenchen. All rights reserved. 
// 
 
#import "ViewController.h" 
 
@interface ViewController () 
 
@end 
 
@implementation ViewController 
 
- (id)initWithCoder:(NSCoder *)aDecoder{ 
  if (self = [super initWithCoder:aDecoder]) { 
    NSLog(@"initWithCoder Called"); 
  } 
  return self; 
} 
- (void)viewDidLoad { 
  [super viewDidLoad]; 
  NSLog(@"viewDidLoad Called"); 
  // Do any additional setup after loading the view, typically from a nib. 
   
} 
- (void)viewWillAppear:(BOOL)animated{ 
  [super viewWillAppear:animated]; 
  NSLog(@"viewWillAppear Called"); 
} 
 
-(void)viewDidAppear:(BOOL)animated{ 
  [super viewDidAppear:animated]; 
  NSLog(@"viewDidAppear Called"); 
 
} 
 
-(void)awakeFromNib{ 
  NSLog(@"awakeFromNib Called"); 
} 
 
-(void)viewWillLayoutSubviews{ 
  NSLog(@"viewWillLayoutSubviews Called"); 
} 
-(void)viewDidLayoutSubviews{ 
  NSLog(@"viewDidLayoutSubviews Called"); 
} 
 
@end

然后，在模拟器上运行，输出为

复制代码

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2014-12-29 19:42:47.904 KVCForCSDN[2370:126741] initWithCoder Called 
2014-12-29 19:42:47.907 KVCForCSDN[2370:126741] awakeFromNib Called 
2014-12-29 19:42:47.927 KVCForCSDN[2370:126741] viewDidLoad Called 
2014-12-29 19:42:47.927 KVCForCSDN[2370:126741] viewWillAppear Called 
2014-12-29 19:42:47.961 KVCForCSDN[2370:126741] viewWillLayoutSubviews Called 
2014-12-29 19:42:47.963 KVCForCSDN[2370:126741] viewDidLayoutSubviews Called 
2014-12-29 19:42:47.970 KVCForCSDN[2370:126741] viewDidAppear Called

所以，调用顺序为

1 init函数(init;initWithFrame;initWithCoder;等)－－初始化
2 awakeFromNib－－在loadView之前的工作放在这里
3 viewDidLoad－－注意，一个ViewController一个生命周期内这个函数只会调用一次
4 viewWillAppear －－ view将要出现，每次View消失再出现都会调用
5 viewWillLayoutSubviews－－简要对子试图进行布局
6 viewDidLayoutSubivews－－完成对子试图布局
7 viewDidAppear－－视图将要出现在屏幕上

－－－上述代码不含部分

8 viewWillDisappear－－View将要消失
9 viewDidDisappear－－View已经消失

这九个就是通常的视图控制器生命周期内函数调用顺序，一定要清楚什么样的代码应该放在视图控制器生命周期的什么位置
BTY：

didReceiveMemoryWarning

这个函数通常也在生命周期的考虑范围内，当内存不足时候会调用，这时候应当进行适当的内存释放，不然iOS会强制关闭当前的APP

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