In order to improve performance i am creating subviews for my scroll view in a background thread and then posting the event to main thread using performSelectorOnMainThread
and adding the view into the scrollview in it and bring it to font. However i get a crash sometimes.
When i check this in my background thread.
if( nil == myView.view.superview)
How can i perform this check thread safe in the background thread. If i have to perform on main thread then i need to change the design a lot, hence can there be a way i post it to main thread and use the return value. I am open to alternatives on the same.
TIA,
Praveen S
EDIT:
I have implemented UIScrollview with paging. However due to performance issues and to improve responsiveness of the UI i moved creating the subviews into a different thread using
[self performSelectorInBackground:@selector(loadPages:) withObject:nil];
In load pages, i do the following
if( nil == myView.view.superview)
{
Create the view
[[self performSelectorOnMainThread:@selector(refreshViews:) myView.view waitUntilDone:YES];
}
In refresh view i add the subview to scrollview and bring it to front.
[myScrollView addSubview:views];
[myScrollView bringSubviewToFront:views];
However the get added and page control works fine. Scrolling is ok ok kind smooth. But when i scroll it fast( swipe across the screen in a fast manner) the application crashes.
The debugger says the crash is at obj_msgSend after the if check in the loadpages.
EDIT: Stack trace -- Well it crashed at the check @synchronized this time. I have edited the crash log to remove project specific names for security reasons but the trace is as below.
#0 0x33a06464 in objc_msgSend ()
#1 0x314d6984 in -[UIViewController _loadViewFromNibNamed:bundle:] ()
#2 0x3开发者_开发百科14d5cb8 in -[UIViewController loadView] ()
#3 0x313d6226 in -[UIViewController view] ()
#6 0x00009920 in -[myViewController loadPages:] (self=0x12a2a0, _cmd=0x1eac1, abcd=0x0) at
#7 0x302d9198 in -[NSThread main] ()
#8 0x302d2248 in __NSThread__main__ ()
#9 0x3110c88c in _pthread_start ()
#10 0x31101a90 in thread_start ()
UIKit is not thread-safe unless specifically marked otherwise. Creating views (and loading nibs) in the background is not supported; anything that touches a UIView needs to happen on the main thread. This applies even before your view has been added to a superview.
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