ios - 递归调用viewDidLoad，崩溃

Question

在loggerViewController.m中:

- (void)viewDidLoad
{
    [super viewDidLoad];
    UIView* mainView = [[UIView alloc] initWithFrame:[UIScreen mainScreen].bounds];
    [self.view addSubview:mainView]; // <-- Problem is here
}

loggingViewController 是我的 appDelegate 的 iVar

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    .
    .
    loggingViewController = [[loggerViewController alloc] init];
    [loggingViewController.view setBackgroundColor:[UIColor blueColor]];
//    [loggingViewController loadView];
    [self.view addSubview:loggingViewController.view];

}

我期待我的 AppDelegate 调用loggingViewController，而loggingViewController又会在内部设置它自己的 subview ，然后就完成了。但是 viewDidLoad 被递归调用，我不明白为什么？

Answer 1

像这样尝试一下，

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
    loggingViewController = [[loggerViewController alloc] init];
    self.window.rootViewController = loggingViewController;
    [self.window makeKeyAndVisible];
}

递归调用的原因是您的 self.view 为 nil，因此当您尝试将其添加为 subview 时，它会尝试一次又一次地调用appdelegate 的 View 。

- (void)viewDidLoad
{
    [super viewDidLoad];
    UIView* mainView = [[UIView alloc] initWithFrame:[UIScreen mainScreen].bounds];
    [self.view setBackgroundColor:[UIColor blueColor]];
    [self.view addSubview:mainView];
}