delegates

问题 Coordinator pattern is an old topic with many libraries trying to solve it and I am learning it in simple example app. My current set up is 3 rootViewControlers: LoadingStateCoordinator , WelcomeCoordinator , TabBarCoordinator but missing connection between UIKit and coordinators. I am trying to implement it with a UINavigationController but the button is not being called. I need a way to connect to back button and a reusable coordinator that I could push to and dellocate accordingly (that is

问题 Are anonymous methods defined inline ? In the example below, the delegate object "d" is having reference of an anonymous method, which is accessing "x" variable which is defined in the Fun method. The scope of "x" should be limited to Fun method, but when we call MyFun, which invokes the delegate passed as parameter and increments the value of "x". The output comes out to be "6", how does this happen ? How the value of "x", or in first place "x" variable itself was available in the anonymous

问题 I was told that Invoke() is similar to normal method calling... so why would people choose to use Invoke and not normal method calling? I tried to search online regarding the issue, what i get is the advantages of using BeginInvoke(), but what are the advantages of using Invoke()? 回答1: Use BeginInvoke when you want to call the delegate asynchronously (on a thread drawn from the thread pool) and Invoke if you want to call it synchronously. 回答2: It's worth noting first that we have to have

问题 I have been trying to run the following script on ImageMagick on a Linux server convert resized.png -gravity Center -crop 1024X768+0+0 +repage flower.png but have been hitting the following error: convert: no decode delegate for this image format `PNG' @ error/constitute.c/ReadImage/501. convert: no images defined `flower.png' @ error/convert.c/ConvertImageCommand/3212. It looks like there is no delegate for PNG. When I run: identify -version I get this result that shows that the PNG delegate

问题 Like many people, I have a splash screen that animates off to reveal the first view of my app. I've been reworking this for the iPad and if you are holding the device in portrait or landscape modes, everything works as intended, the correct default image is used, the correct image that is used to animate this off is used, all orientations work fine. BUT If I get the device into landscape mode, and then lay it flat on the table, things go wrong. The correct splash screen is used, but the image

问题 Like many people, I have a splash screen that animates off to reveal the first view of my app. I've been reworking this for the iPad and if you are holding the device in portrait or landscape modes, everything works as intended, the correct default image is used, the correct image that is used to animate this off is used, all orientations work fine. BUT If I get the device into landscape mode, and then lay it flat on the table, things go wrong. The correct splash screen is used, but the image

问题 Why did Apple choose to use delegation for some communication amongst SDK objects and to post notifications to Notification Center for others? In particular, I'm thinking about the set of keyboard appearance notifications that come from UIWindow. Is it because the Notification Center system means that more than one object can use the keyboard appearance action as a trigger to change its state, whereas only one object would have been able to act with a delegate implementation? 回答1: Delegation

问题 Why did Apple choose to use delegation for some communication amongst SDK objects and to post notifications to Notification Center for others? In particular, I'm thinking about the set of keyboard appearance notifications that come from UIWindow. Is it because the Notification Center system means that more than one object can use the keyboard appearance action as a trigger to change its state, whereas only one object would have been able to act with a delegate implementation? 回答1: Delegation

问题 All of my code is in AppDelegate.m: - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { self.window = [[UIWindow alloc]initWithFrame:[[UIScreen mainScreen]bounds]]; _locationMgr = [[CLLocationManager alloc] init]; [_locationMgr setDelegate:self]; if([_locationMgr respondsToSelector:@selector(setAllowsBackgroundLocationUpdates:)]) [_locationMgr setAllowsBackgroundLocationUpdates:YES]; CLAuthorizationStatus authorizationStatus=

问题 All of my code is in AppDelegate.m: - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { self.window = [[UIWindow alloc]initWithFrame:[[UIScreen mainScreen]bounds]]; _locationMgr = [[CLLocationManager alloc] init]; [_locationMgr setDelegate:self]; if([_locationMgr respondsToSelector:@selector(setAllowsBackgroundLocationUpdates:)]) [_locationMgr setAllowsBackgroundLocationUpdates:YES]; CLAuthorizationStatus authorizationStatus=