On Nov 21, 2008, at 11:15 AM, Marc Stibane wrote:

Am 19.11.2008 um 10:05 schrieb mmalcolm crawford:

On Nov 18, 2008, at 10:33 AM, Marc Stibane wrote:
Lets forget for a moment that the dealloc never get's called at all on the iPhone
This is simply untrue.
Nope.
Try to set a breakpoint inside the dealloc in the same file as applicationDidFinishLaunching, run your app and press the home button. Never called, and purposely so - the application finishes anyway, so why spend cycles deallocating small blocks one-by-one when you can just throw away all memory the app used in one block...

I'm perfectly well aware of that optimisation; as an unconstrained statement, however, "dealloc never get's called at all on the iPhone" is untrue. There are many situations when dealloc *will* be called, and so you should take that into account.


Because:
Cocoa strongly advocates you use accessor methods to set instance variables(*); You are discouraged from setting instance variables directly anywhere other than in initializers and dealloc(*);
For me, applicationDidFinishLaunching IS an initializer...

You're free to hold your own views; as far as Cocoa is concerned, however, it is *not* an initialiser.


On iPhone in particular, you should avoid the use of autorelease.
The latter point in particular means that this alternative:
  self.viewController = [[[UIViewController alloc]
initWithNibName:@"MoveMeView" bundle:[NSBundle mainBundle]] autorelease];
does not follow best practice.
Thus -- almost by a process of elimination -- you're left with the pattern shown in iPhone samples.

I stick with my applicationDidFinishLaunching implementation - 1 line instead of 3.

Again you're welcome to do so, and you're welcome to deal with any bugs that arise as a result.

Of cause you're right were it some other method which could be called more than once and not applicationDidFinishLaunching, which is only called once and - as stated above - never paired with dealloc (however, applicationWillTerminate is called).

@interface MyObject : MySuperClass {
    NSString *string;
}
@property (nonatomic, retain) NSString *string;
@end;

@implementation MyObject
@synthesize string;

- (id)init {

    if (self = [super init]) {
// a poor example for several reasons, but take this just as a way
        // to crease a new, owned, object
string = [[NSString alloc] initWithFormat:@"now: %@", [NSDate date]);
    }
    return self;
}

- (void)applicationDidFinishLaunching:(UIApplication *)application {

string = [[NSString alloc] initWithFormat:@"now: %@", [NSDate date]);
}

You just leaked the first value of string.

And to preempt the assertion that "this would never happen" -- precisely this *did* happen to someone else who made exactly your point, within a week of their having made it.

mmalc




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