iOS: How to remove object from memory with ARC enabled?

问题

I am developing an iOS app with the iOS 5 SDK, Automatic Reference Counting is enabled. But I have a specific object that is being created in large numbers and must be released after a second because otherwise the device will become very slow. It looks like they are not released, as the device is very slow. Is there a way to manually release an object when ARC is enabled?

EDIT: My code, this is called 200 times a second to generate sparkles. They fade out after 0.8 seconds so they are useless after then.

    int xanimationdiff = arc4random() % 30;
    int yanimationdiff = arc4random() % 30;
    if (arc4random()%2 == 0) {
        xanimationdiff = xanimationdiff * -1;
    }
    if (arc4random()%2 == 0) {
        yanimationdiff = yanimationdiff * -1;
    }

    Sparkle *newSparkle = [[Sparkle alloc] initWithFrame:CGRectMake(20 + arc4random() % 280, 20, 10, 10)];
    //[newSparkle setTransform:CGAffineTransformMakeRotation(arc4random() * (M_PI * 360 / 180))]; //Rotatie instellen (was niet mooi, net sneeuw)
    [self.view addSubview:newSparkle];
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.8];
    [newSparkle setFrame:CGRectMake(newSparkle.frame.origin.x - xanimationdiff, newSparkle.frame.origin.y - yanimationdiff, newSparkle.frame.size.width, newSparkle.frame.size.height)];
    newSparkle.alpha = 0;
    [UIView commitAnimations];

The sparkle object code:

#import "Sparkle.h"

@implementation Sparkle

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        [self setBackgroundColor:[UIColor colorWithPatternImage:[UIImage imageNamed:@"sparkle.png"]]];
    }
    return self;
}

@end

回答1:

Object* myObject = [[Object alloc] init];     
myObject = nil; // poof...

EDIT: You cannot directly control when an object is released BUT you can indirectly cause it to happen. How? Remember what ARC does EXACTLY. Unlike human coding convention, ARC parses your code and inserts release statements AS SOON AS OBJECTS CAN be released. This frees up the memory for new allocations straight away, which is awesome/necessary. Meaning, setting an object to nil, or simply allowing a variable to go out of scope ... something that CAUSES A 0 RETAIN COUNT forces ARC to place its release calls there. It must ... because it would leak otherwise.

回答2:

Just surround the section of code that is going to be called 200 times with an @autoreleasepool { ... } statement. This will cause the memory to be deallocated immediately as opposed to waiting for the control to go all the way back up the event chain to the top level autorelease pool.

回答3:

I found the answer, it was actually really stupid. I didn't remove the sparkles from the superview. Now I remove them after 0.8 seconds with a timer and it performs great again :)

回答4:

With ARC you cannot call dealloc, release, or retain, although you can still retain and release CoreFoundation objects (NB: you can implement dealloc methods for your own custom subclasses, but you can't call super dealloc). So the simple answer is 'no', you unfortunately cannot manually release an object when using ARC.

I'd double check you're sure they're not being released, because in theory if you no longer reference an object it should be released. What do you do with these objects once you create them? You simply create them then immediately destroy them?

Perhaps you could post the code you're using / the property declarations - are these weak or strong referenced objects?

来源：https://stackoverflow.com/questions/7631643/ios-how-to-remove-object-from-memory-with-arc-enabled

标签

ios

automatic-ref-counting