I'd like to know the exact moment when screen frame finishes rendering and gets displayed, so I can capture specific window images with quartz api. There is CVDisplayLink / CADisplayLink that allows application to synchronise its drawing to the refresh rate of the display.
As I understand, those methods are very similar to what I need, but invoked when screen frame needs to be rendered, not when it finished and presented, meaning that if I capture the current screen image at that time I'd only see the previous render. Is this correct thinking?
If yes, is there a way to do get notified when the frame has actually finished rendered and was presented? Maybe there's private api for that? Ideally I need an answer for macOS, but if you happen to know how to do this in iOS, please let know.
P.S. I'm aware of CGDisplayStream, it's a great solution for capturing the whole screen, not specific windows – it uses run loops and dispatch queues, meaning that callbacks are not invoked in realtime like with display links.
Related
I want to implement animation like This link while application interact with server.
If someone has example to implement this kind of animation then please provide me link.
Start animation
Server request in background thread
End animation in completion block of server request in the main thread
If you want that specific one I think you are going to have to make it yourself, but if you don't here are some open source alternatives.
DGActivityIndicatorView
MONActivityIndicatorView
YRActivityIndicator
interaction designer at Creativedash here =]
For something like that you'd make a png sequence, and set the animationImages property of a UIImageView. iOS is great at animating png sequences.
When your load starts, do yourLoadingImage.startAnimating() and when it's over (in the completion for your request), call yourLoadingImage.stopAnimating().
There's a property called animationDuration, and you need to set that as well, just to indicate how long the animation loop is - this doesn't indicate how long the animation will play for. It loops until you tell it to stop.
yourLoadingImage.animationDuration = 1 //set the loop duration to 1s
We actually did a short blog post on this process, and it can be the same for really any custom loader. http://news.ui8.net/create-a-custom-animated-loading-indicator-with-swift/
I want to have some information drop down from the top of a view, stay on the screen for a second or two, and then go back up out of the view. I have search for displaying notifications and/or banners. All I get is either push notifications (which I don't need to use) or iAds banners.
I'm working on a barcode scanning app and I want to briefly show the value of the barcode shown without requiring the user to tap on anything. How can I accomplish this?
Don't use notifications and banners, because that might not work: the user can turn them off. In any case this is not a notification of anything, so it's a misuse of notifications.
Just do what you described, yourself: animate a view onto the screen, and then (in the animation's completion handler) use delayed performance to animate the view right back off the screen after a short delay.
You should use a view which manages its own state (INCOMING, STAY PUT, OUTGOING). This way you can reduce the memory footprint and many other bugs in the process. I coded something for a similar process. Check it out
It seems like the fade animation between the launch screen and my first view is really slow.
I don't think it used to be like that. Is there a way to control the speed of that transitional animation?
I looked at some apps on my phone and the launch screen doesn't fade as slowly as mine. What things could I have done to affect that?
(No I don't have slow animations turned on, only the fade animation is slow)
In WWDC 2012 video iOS App Performance: Responsiveness they enumerate a whole list of issues that have impact on the app startup time, ranging from attaching to unnecessary frameworks, optional linking to frameworks that you really could make required, the use of static initializers, overly complicated initial scenes, too much information stored in preferences, etc.
That video covers a range of topics, like the above, which impact startup time. In the demonstration, they show how one might benchmark the startup time. Unfortunately, in my experience, there's a good chance that you might not be able to do anything to fix this issue (e.g. you need certain features and therefore need certain frameworks), but it's still an illuminating video and it might give you some ideas of things you can try to alleviate the start-up performance issues.
If your app splash screen show more time, so please check following things in your app.
1. AppDelegate.m
in didFinishLaunchingWithOptions method have you called any heavy method which takes more time for finish task if yes then change that method location, basically in appDelegate class don't write any heavy methods.
2. first view of your app.
check viewDidLoad() method, if you call many method or any heavy method from here then your launch image will show still your control not come out from viewDidLoad method, so if you want call any methods at view launch time then call them from viewWillAppear or viewDidAppear method (in viewDidAppear method don't call any UI related methods)
I never figured out what was going on here, but the next day when I started up xCode and the simulator it was back to the normal loading time.
I know it's not recommended to change any view appearance when the application is moved to background state, but for my specific task I cannot postpone this activity and I really like to complete it in a couple of seconds after the user hits the home button.
That's what I do:
I load a webpage in a UIWebView and after loading completion I change the contentOffset and zoomScale in order to make a specific screenshot of that webpage. When the app is in active application state everything works fine.
Now I wanted to add some more multitasking capabilities. I encapsulated the above described webpage loading and rendering activity in a protected background task (iOS Task Completion), in order to complete it even when the user hits the home button.
I have noticed that the page loading and the rendering of the webpage screenshot (with the renderInContext: method) works just fine in background, BUT it seems that the webview (i.e. the encapsulated UIScrollView instance) does not react on setContentOffset: and setZoomScale: messages as soon as the app is in background..
So I'm asking you if you know any alternatives to change the content offset / zoomscale? (modifications directly on CALayer?) Or any method to "force" the scrollview to perform the content changes even in background.
PS: On the iOS simulator everything works fine even in application background state, but on real devices it does not.
EDIT: I have created a simple demo project that demonstrates the issue. You can download it here (please read the instructions in the zip file): http://dl.dropbox.com/u/3556271/BackgroundBugDemo.zip
I appreciate every hint or tip. Thanks!
I have an app that generates a PDF and displays it at the same time. As expected, there is about a 2-second delay between pressing the "Generate PDF" button and the QLPreviewController presenting the document. Not only that, it appears as though the document fades in momentarily, freezes, and then completes the fade-in.
I understand that the reason for the delay is because it is generating the PDF first, but the design of the application doesn't allow for any other mechanism. I was hoping to put a brief "LOADING..." animation before the QLPreviewController view appears, but everything I've tried so far still presents a 2-second delay.
Can anyone provide guidance on what I might be able to do here?
There are lots of options. I'd suggest that whatever you do, it be asynchronous. This will allow for the UI to not 'freeze' and you can put a loading screen up even if it is for 2 seconds.
There are many ways to implement this. Some involve actual background threads and others don't.
You can use, delegates, NSNotifications, blocks, NSOperations, and/or Grand Central Dispatch.
Here's a tutorial on how to use Grand Central Dispatch
Here's a tutorial on blocks