CODEWITHSUNDEEP
iphoneuser-interface
James
James

Reputation: 229

How to avoid UI freezes?

Im trying to find the best way to avoid having tiny UI lockups after certain events in my app. For example here are two cases where i have come across mini-lockups:

  1. I have a button that when pressed loads a local mp3 file (around 20-30mb) using AVAudioPlayer, calls the prepareToPlay method and then plays the audio file. The issue is that the button has the showsTouchWhenHighlighted flag set to yes and after pressing it it stays highlighted until the audio file begins playing which could take 1-3 secs.

  2. Another similar example is using a navbar button to sort and reload the table data. There is a very short but noticeable lockup where the button remains highlighted until the table has reloaded.

Can anyone suggest a good approach to minimizing/eliminating these mini lockups? I didnt really come across any code to achieve this in any of the books/tutorials i read that dealt with tableviews and avaudioplayer. Should i be launching these actions on different threads?

thx

Upvotes: 1

Views: 806

Answers (2)

linusthe3rd
linusthe3rd

Reputation: 3566

I'm an iPhone noob myself, but it sounds like your code is stuck doing synchronous actions, which will guarantee that your UI gets locked up until the action is done executing.

Although I don't have an explicit answer, look for asynchronous options to perform these actions as they will not lockup your UI. These are usually achieved through using threads or deferred objects. From my experience so far w/ Objective-C, most actions your program neds to take can be achieved through async actions.

Upvotes: 1

Malaxeur
Malaxeur

Reputation: 6043

For number 1, your best bet is to load the item on a background thread and inform the user that you're doing so (either via a loading HUD or some other indicator). The simplest way of doing this will be to use - (void)performSelectorInBackground:(SEL)aSelector withObject:(id)arg;. If you're running iOS 4.0 + you may want to look into executing block callbacks and see if they will work for you.

For number 2, perform the sorting on the background thread or change your sorting method (consider using a sorted data structure rather than resorting after inserts?). reloadData should occur only on the main thread.

Upvotes: 2

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