uiviewcontroller

问题 I'm trying to switch from Objective-C to Swift. I don't understand the point of declaring a function to return a AnyObject! instead of AnyObject? . For example: func instantiateViewControllerWithIdentifier(identifier: String) -> AnyObject! Why does this method return an implicitly unwrapped optional and not a simple optional? I get the AnyObject part, but what's the point of allowing us to avoid using the ! to unwrap the optional if it may be nil? (thus crashing the app, even if it's very

问题 I'm trying to switch from Objective-C to Swift. I don't understand the point of declaring a function to return a AnyObject! instead of AnyObject? . For example: func instantiateViewControllerWithIdentifier(identifier: String) -> AnyObject! Why does this method return an implicitly unwrapped optional and not a simple optional? I get the AnyObject part, but what's the point of allowing us to avoid using the ! to unwrap the optional if it may be nil? (thus crashing the app, even if it's very

问题 I'm trying to switch from Objective-C to Swift. I don't understand the point of declaring a function to return a AnyObject! instead of AnyObject? . For example: func instantiateViewControllerWithIdentifier(identifier: String) -> AnyObject! Why does this method return an implicitly unwrapped optional and not a simple optional? I get the AnyObject part, but what's the point of allowing us to avoid using the ! to unwrap the optional if it may be nil? (thus crashing the app, even if it's very

问题 I'm trying to switch from Objective-C to Swift. I don't understand the point of declaring a function to return a AnyObject! instead of AnyObject? . For example: func instantiateViewControllerWithIdentifier(identifier: String) -> AnyObject! Why does this method return an implicitly unwrapped optional and not a simple optional? I get the AnyObject part, but what's the point of allowing us to avoid using the ! to unwrap the optional if it may be nil? (thus crashing the app, even if it's very

问题 This question already has answers here : Closed 7 years ago . Possible Duplicate: iPhone CATransition adds a fade to the start and end of any animation? I'm trying to duplicate the "slide up from the bottom" animation that [UIViewController presentModalViewController:animated:] performs but without calling it because I don't want a modal view. The below core animation code comes very close but appears to be changing transparency values of the views during it. At the start of the animation you

问题 For some reason in Xcode 8.1, all my storyboards are now blank, with boxes around where the content used to be: I tried cleaning, deleting the Derived Data folder, and changing the size to Freeform but nothing has worked. How do I fix this? 回答1: Try these: Delete your derived data. Close xcode and clean, build again. If option 1 not work then, Copy your project to another directory/folder. Close Xcode, open project from new directly and clean, build. 来源： https://stackoverflow.com/questions

问题 For some reason in Xcode 8.1, all my storyboards are now blank, with boxes around where the content used to be: I tried cleaning, deleting the Derived Data folder, and changing the size to Freeform but nothing has worked. How do I fix this? 回答1: Try these: Delete your derived data. Close xcode and clean, build again. If option 1 not work then, Copy your project to another directory/folder. Close Xcode, open project from new directly and clean, build. 来源： https://stackoverflow.com/questions

问题 I have a function in my app delegate which appends an item to an array in my a file named ViewController.swift, and then I want to reload a tableview in that same file. I attempt to do so like so: let vc = ViewController() let navigationController = UINavigationController(rootViewController: vc) window!.rootViewController = navigationController println(vc.messages) //1 vc.messages.append(message.data.message as! String) //2 vc.MessageTableView?.reloadData() The lines numbered 1,2 are where I

问题 I have a function in my app delegate which appends an item to an array in my a file named ViewController.swift, and then I want to reload a tableview in that same file. I attempt to do so like so: let vc = ViewController() let navigationController = UINavigationController(rootViewController: vc) window!.rootViewController = navigationController println(vc.messages) //1 vc.messages.append(message.data.message as! String) //2 vc.MessageTableView?.reloadData() The lines numbered 1,2 are where I

问题 I am implementing ECSlidingViewController in my app. Everything works fine, when I hit the menu button (UIBar) the left menu slides. But pressing the menu button again does not bring back the current ViewController . It works in the sample app, but I cannot find that line of code that brings back the current controller. Here is the code to show the menu: - (IBAction)menuButtonTapped:(id)sender { [self.slidingViewController anchorTopViewToRightAnimated:YES]; } Now I am looked everywhere for