�ݺ�ߣ

Why we should use thread and how to do it
with no additional efforts.

? Dominik Haska �C Research Software
Developer in Jeppesen a Boeing Company
? 9 years of professional programming
including 1 year in IOS

? Why
? Moore law and physics limitations
? How
? how to use the potentially power of multicore
devices easily and properly

2013-05-15 threads. why and how

? iPhone 1 �C 1 CPU 412 MHz
? iPhone 5 �C 2 CPU 1300 MHz
? iPad 1 �C 1 CPU 1000 MHz
? iPad 4 (retina) �C 2 CPU 1400 MHz

? all animations:
? GPU is a massive multiprocessor unit
? Just use the animation block
[UIView animateWithDuration:1.0 animations:^{
firstView.alpha = 0.0;
secondView.alpha = 1.0;
}];

[UIView beginAnimations:@"ToggleViews" context:nil];
[UIView setAnimationDuration:1.0];
// Make the animatable changes.
firstView.alpha = 0.0;
secondView.alpha = 1.0;
// Commit the changes and perform the animation.
[UIView commitAnimations];

? Animation block stops user interaction during
animation
? animateWithDuration:delay: options:
animations:completion:
? UIViewAnimationOptions:
? UIViewAnimationOptionAllowUserInteraction
? UIViewAnimationOptionBeginFromCurrentState
? [self.layer removeAllAnimations];

? CGRect animatedFrame =
[self.animatedView.layer.presentationLayer
frame];
? CGRect targetFrame = self. animatedView.frame;
? if(animatedFrame.origin.x != 0.0 ||
animatedFrame.origin.y != 0.0){
CGFloat xMis = animatedFrame.origin.x �C
targetFrame.origin.x;
CGFloat yMis = animatedFrame.origin.y -
targetFrame.origin.y;
[fix the position];
}

? Create property with quee
? [NSOperationQueue new];
? Create invocation
? NSInvocationOperation *operation =
[[NSInvocationOperation alloc] initWithTarget:self
selector:@selector(calculate) object:nil];
? Add operation to quee
? [self.renderingQueue addOperation:operation];
? Or remove (cancelAllOperations)

? Some code have to be executed in main
thread
? [NSString sizeWithFont] �C sometimes �C once
per 1-2 day crashes app
? [[UIView alloc] init]
? [view addSubview��]
? Solution
? Delegate and perform on main thread
performSelectorOnMainThread:@selector(
? Use NSAttributedString to work with UIKit Additions
? Always check when app crashes in which thread are
you

? dispatch_async(dispatch_get_global_qu
eue(DISPATCH_QUEUE_PRIORITY_DEFAULT),
^{
your code here
}

? Long time for response
? Multiple resources needed in parraler
(webbrowsers)
? Ready to use in ios:
? [SSLConnection
sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse*
response, NSData* data, NSError*
error){ �� }

? You have multicore devices �C use this
? Look for simplest solution �C use library as
much as possible
? Focus on user interaction �C do not freeze your
apps
? Be carefull with debugging �C single thread
app is much more testable �C much much
more
? I work for jeppesen boeing company �C if i
show you sample code I have to kill you ;) �C
but next time I try to be better

? developer.apple.com
? http://www.gotw.ca/publications/concurrenc
y-ddj.htm - the free lunch is over
? http://www.robotswillstealyourjob.com/ -
robots are stealing your job �C and engineers
help them to
? http://www.extremetech.com/computing/11
6561-the-death-of-cpu-scaling-from-one-
core-to-many-and-why-were-still-stuck/2

�ݺ�ߣ

2013-05-15 threads. why and how

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2013-05-15 threads. why and how