IOS视图控制器的生命周期

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http://blog.csdn.net/hello_hwc?viewmode=contents

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

//
//  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

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