My iOS app launch screen takes about 3 - 5 seconds. I have a map that will load after the launch screen. My users have to wait for the launch screen to load and then wait another 3 seconds for the map to load.
Is there a way to minimize launch screen time?
Basically this delay means that you are doing something very wrong during launch. Your job is to launch immediately. Indeed, the WatchDog app will kill you dead if you don't.
There are excellent WWDC videos on this topic, and you should watch them. But in general there are two ways to go wrong:
You must do nothing time-consuming on the main thread. If you have a time-consuming thing to do, like loading your map or networking, you must do that on a background thread. You need to get out of the way so that the runtime can launch your app now.
Just the other way around, you must not touch the interface on any other thread but the main thread. Doing this wrong causes just the kind of delay you are reporting. Do your work on a background thread, but then get back on the main thread to talk to your views, view controllers, etc.
Finally, I should point out that you might be able to get some idea what you're doing wrong by using Instruments. Unfortunately it works rather badly against app launch, but it can be worth a try. Above all, watch those videos!
Related
I have an iOS Xcode project that previously would load fast, but from time to time, now will hang for five seconds or more during loading. When the app is run on an iPhone, the launch screen displays instantly, but sometimes, not always, and unpredictably, the app just hangs for around 5 seconds or more until the actual interface is displayed. It occurs both on the simulator and device across different iOS versions 7, 8, 9.
Recently, a UIView's class that contains a drawRect function was changed slightly, it has an outlet connection to one of the ViewControllers, but no significant changes made overall. One ViewController has code in the ViewDidLoad, ViewWillAppear, ViewDidAppear functions. All these things I'm investigating if they are impacting the load time.
When I terminate the app, the next time I try running it, it loads super fast without issue. I have no idea what to make of this load behaviour.
Questions
1 - What methods can I use in Xcode to debug an app that loads slowly at irregular and unpredictable times?
2 - What obvious items should I be on the look out in the project that typically cause slow or prolonged load times?
3 - Does Xcode include tools to monitor the processes operating live while loading occurs?
4 - Is it possible to print output for load processes I can review?
Any experienced advice really appreciated. Thanks.
Not sure if you have looked instrumentation. It is the best way to determine this kind of issues with your app.
https://developer.apple.com/library/watchos/documentation/DeveloperTools/Conceptual/InstrumentsUserGuide/index.html
When I terminate the app, the next time I try running it, it loads super fast without issue. I have no idea what to make of this load behavior.
Do you mean exiting the app? Or actually killing it? Cause if it is the former, then the reason is the app was just launched from a suspended state.
I would suggest take a closer look at didFinishLaunchingWithOptions:, and check if you are doing something that takes more time than needed. Run your app with the time profiler instrument, it will tell you where is your bottleneck.
I'm having an issue with this code (I have it in didFinishLaunchingWithOptions). I need it to finish executing the code inside before the app continues because it sets up some critical things in core data. It sends this to the background though and starts running the rest of the app and it doesn't finish quick enough for the data to be usable.
DataManager.getDataWithSuccess { (data) -> Void in
//code to execute here
}
How can I force the app to wait for this code to finish before moving on?
You shouldn't block the didFinishLaunchingWithOptions method from returning so that it can wait on an asynchronous task. It's crucially important to note that iOS applications are only given a limited amount of time to complete launching before the application is killed by the operating system.
An approach I have used in the past when waiting on asynchronous things to happen that need to happen before I really launch my app is to create a LaunchViewController. The interface for this view controller matches perfectly to the app's splash screen. From an end-user perspective, you can't even tell we've left the splash screen.
Here, we do any set up code such as asking your DataManager to get data. Then, when it (and any other set up actions) completes, you simply present the next view controller in much the same way you'd move between any other view controllers.
A huge positive side effect here is that you can have much nice looking animations from your splash screen into the first screen of your application.
While attempting to optimize load speed I started placing timers in different places and looking at the performance. The app uses OpenGL and Core Data and has a decent amount of screens and artwork.
But the largest part of the lag seems to be taking place prior to applicationWillEnterForeground (assuming it's not a cold load)
The app shows up and is displayed and the UI is unresponsive for close to 5 seconds. I start a timer and print a time as soon as I can press a button. The time between applicationWillEnterForeground and when I can press the button is 200 milliseconds.
What can be causing my application to be slow to load prior to applicationWillEnterForeground or what can I do evaluate what is happening there? Instruments does not seem to display any information about that part of the launch.
Other testing app I have don't seem the same performance. Is it the bundle size or the amount of memory used by the application? Loading dynamic libraries?
This was related to OpenAL. The app was not closing the OpenAL context and for some reason this caused considerable problems when closing and reloading the app. The app uses CosCos Denshion so I to make sure to call these.
[CDAudioManager end];
[SimpleAudioEngine end];
I have noticed that during very processor or memory intensive processes that my app is running, notably during initial download or executing a query, the clock inside the status bar will stop running and stay at the time that the process started. Is there any way to prevent this from happening, in case something like this causes the app to be rejected? I don't have any code to provide, as I am unsure to where the app does this at exactly.
Considering your comment, you should not perform memory-intensive or cpu-intensive work on the main thread. Only interactions with UI should be performed on the main thread, otherwise the UI will seem frozen, including your app and status bar.
This is very difficult issue, since it doesn't occur every time.
When an app is just launched, returning from background, it is fine without any freezing.
After some time being in background, when I re-activate it, the whole UI is frozen for while, even the activity indicator is not animating. As time goes on, this freezing gets longer and finally causes the app to be terminated by iOS for not resuming in time.
I would like to learn what are the generic causes of an app to be unresponsive, especially if the app is supporting background running feature and re-activating after a period of being in background.
It looks like I have missed some fundamental techniques that should be respected to avoid freezing problems.
UPDATE: I am suspicious if saving UIImage into Core Data object can be the main reason. At launch, it's not visible, however, as time passes, numerous saveManagedObjectContext are performed while UIImage is still referenced.
Maybe I should have listened to the instruction not to save any image in Core Data?
check for your crash log if you are getting this
Exception Codes: 0x8badf00d
then its most probably your application is taking much time either in launch or while moving in background or terminate, actually app take much time in launch/shut iOS suspend it and our app freeze, there is no such time define in documents but as i experienced it should not be more then 4-5 seconds. check your app delegate applicationDidFinishLaunch or multitasking delegates there is some code which is taking time in completion. For more info lokk at these
http://developer.apple.com/library/ios/#technotes/tn2151/_index.html
http://en.wikipedia.org/wiki/Hexspeak