Question

我正在尝试为我的init编写自定义UIViewController方法。这是方法本身：

- (instancetype)initWithBottomViewController:(UIViewController *)bottomViewController andTopViewController:(UIViewController *)topViewController {
    self = [super init];
    if (self) {
        self.bottomViewController = bottomViewController;
        self.topViewController = topViewController;
    }

    return self;
}

- (void)setupBottomViewController {
    /*crashes here because self.bottomViewController appears to be nil*/
    [self addChildViewController:self.bottomViewController];
    [self.bottomViewController.view setFrame:self.view.bounds];
    [self.view addSubview:self.bottomViewController.view];
    [self.bottomViewController didMoveToParentViewController:self];
}

控制台说-[__NSArrayM insertObject:AtIndex:] object cannot be nil

我在init中调用AppDelegate.m函数：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    BottomViewController *bottomVC = [[BottomViewController alloc] initWithNibName:@"BottomViewController" bundle:nil];
    TopViewController *topVC = [[TopViewController alloc] initWithNibName:@"TopViewController" bundle:nil];
    SlideMenuController *slideController = [[SlideMenuController alloc] initWithBottomViewController:bottomVC andTopViewController:topVC];
    self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
    self.window.rootViewController = slideController;
    [self.window makeKeyAndVisible];

    return YES;
}

属性self.bottomViewController和self.topViewController在.h文件中声明：

@property (strong, nonatomic) UIViewController *bottomViewController;
@property (strong, nonatomic) UIViewController *topViewController;

问题在于分配给self.bottomViewController和self.topViewController。 bottomViewController和topViewController不是nil，但是self.bottomViewController和self.topViewController是{{1}}。我自己弄不清楚。提前致谢！

Answer 1

问题是我为class Window { private: void constructor_method(int a); void constructor_method(int a, void *b); void constructor_method(string a); public: Window(int a) { constructor_method(a); } Window(int a, void *b) { constructor_method(a, b); } Window(string a) { constructor_method(a); } Window(double a, double b) { if (a * b == 0.0) { constructor_method("ZERO"); } else if (a * b > 100.0) { constructor_method((int) (a + b), x); } else { constructor_method((int) (a + b)); } } };和<body> <form id="form1" runat="server"> <div id="signature-pad" class="signature-pad"> <div class="signature-pad--body"> <canvas></canvas> </div> <div class="signature-pad--footer"> <div class="description">Sign above</div> <div class="signature-pad--actions"> <div> <button type="button" class="button clear" data-action="clear">Clear</button> <button type="button" class="button" data-action="change-color">Change color</button> <button type="button" class="button" data-action="undo">Undo</button> <asp:button text="Save" runat="server" cssclass="button save" data-action="save" onclick="Save" /> </div> <div> <button type="button" class="button save" data-action="save-png">Save as PNG</button> <button type="button" class="button save" data-action="save-jpg">Save as JPG</button> <button type="button" class="button save" data-action="save-svg">Save as SVG</button> </div> </div> </div> </div> <input type="hidden" id="hfSign" runat="server" /> </form> <script src="js/signature_pad.umd.js"></script> <script src="js/app.js"></script> </body>都实现了空的setter方法。

分配给自定义init方法内的属性

1 个答案: