iOS development study notes (OC language) - UIView and UIViewController life cycle

UIView life cycle

#import "ViewController.h"

@interface TestView: UIView

@end

@implementation TestView

- (instancetype)init{
    self = [super init];
    if (self) {
        
    }
    return self;
}

- (void)willMoveToSuperview:(nullable UIView *)newSuperview {
    [super willMoveToSuperview:newSuperview];
}

- (void)didMoveToSuperview {
    [super didMoveToSuperview];
}

- (void)willMoveToWindow:(nullable UIWindow *)newWindow {
    [super willMoveToWindow:newWindow];
}

- (void)didMoveToWindow {
    [super didMoveToWindow];
}

@end


@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    TestView *view = [[TestView alloc] init];
    view.backgroundColor = [UIColor redColor];
    view.frame = CGRectMake(100, 100, 100, 100);
    [self.view addSubview:view];
}

@end

Through breakpoint debugging, you can find that the life cycle is:

1. init
2. willMoveToSuperview
3. didMoveToSuperview
4. willMoveToWindow
5. didMoveToWindow

UIViewController life cycle

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (instancetype)init {
    self = [super init];
    if (self) {
        
    }
    return self;
}

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
}

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    UIView *view = [[UIView alloc] init];
    view.backgroundColor = [UIColor redColor];
    view.frame = CGRectMake(100, 100, 100, 100);
    [self.view addSubview:view];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
}

- (void)viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:animated];
}


@end

Through breakpoint debugging, you can find that the life cycle is:

1. init
2. viewDidLoad
3. viewDidAppear

If removed, the order is:

1. viewWillDisappear
2. viewDidDisappear