UIViewController

最新推荐文章于 2024-09-12 19:33:15 发布

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本文详细解析了UIViewController的生命周期方法，包括初始化、视图加载、显示及消失等关键阶段，并通过实例展示了这些方法的调用顺序。

UIViewController

@property(nonatomic,retain) UIView *view;

ViewContrlller本身不是一个视图, 想要显示的视图必须要放在这个视图上

初始化方法:

- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil;

.h 文件里面引用头文件要用@class避免重复引用, 不要用#import

.m 文件中可以用#import

- (void)viewDidLoad 和

- (void)loadView

将要显示: - (void)viewWillAppear:(BOOL)animated;

已经显示: - (void)viewDidAppear:(BOOL)animated;

将要消失: - (void)viewWillDisappear:(BOOL)animated;

已经消失: - (void)viewDidDisappear:(BOOL)animated;

UIController流程:

程序说明:

现有MainViewController和SecondViewController,
重写MainViewController中的 loadView, viewWillAppear:, viewDidAppear:, viewWillDisappear:, viewDidDisappear:
将MainViewController设为Window的RootViewController, 点击MainViewController上的”点击”按钮,会模态进入SecondViewController,
点击SecondViewController上的返回按钮会返回MainViewController

以下为MainViewController中各个方法的执行顺序:

初始化方法:

- (instancetype)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];

    NSLog(@"初始化方法:initWithNib");
    if (self) {
    }
    return self;
}

loadView:方法:

- (void)loadView{
    [super loadView];
    NSLog(@"%s", __func__);
    NSLog(@"loadView方法");
}

viewDidLoad:方法:

- (void)viewDidLoad {
    [super viewDidLoad];
    NSLog(@"viewDidLoad方法");
    UILabel *label1 = [[UILabel alloc] initWithFrame:CGRectMake(50, 50, 100, 30)];
    label1.backgroundColor = [UIColor greenColor];
    [self.view addSubview:label1];
    [label1 release];
    [self createButton]; —> 通过此方法创建一个UIButton, 点击该button会模态进入SecondViewController
}

viewWillAppear:方法:

- (void)viewWillAppear:(BOOL)animated{ 
    [super viewWillAppear:animated];
    NSLog(@"%s", __func__);
    NSLog(@"将要显示");
}

viewDidAppear:方法:

- (void)viewDidAppear:(BOOL)animated{
    [super viewDidAppear:animated];
    NSLog(@"%s", __func__);
    NSLog(@"已经显示");
}

点击按钮进入下一页进入SecondViewController时:

viewWillDisappear:方法:

- (void)viewWillDisappear:(BOOL)animated{
    [super viewWillDisappear:animated];
    NSLog(@"%s", __func__);
    NSLog(@"将要消失");
}

viewDidDisappear:方法:

<span style="font-size:14px;">- (void)viewDidDisappear:(BOOL)animated{
    [super viewDidDisappear:animated];
    NSLog(@"%s", __func__);
    NSLog(@"已经消失");
}</span>

点击按钮返回MainViewController时: