iOS小技巧->页面关系

@interface BaseViewController : UIViewController

@end

@implementation BaseViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
-(void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    
    NSLog(@"移除 %@ is removeObserver.", [self class]);
}

-(void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    
    NSLog(@"创建 %@ is addObserver.", [self class]);
}