CODEWITHSUNDEEP
iphoneobjective-cmemory
Iuliu Atudosiei
Iuliu Atudosiei

Reputation: 679

iphone objectiveC alloc/release question

I am new to ObjectiveC language. I am having trouble understanding memory management syntax. My code is below:

NSDate* someDate;
someDate=[[NSDate alloc] init];
loop
{ 
   someDate=[[NSDate alloc] init];
}

will I have a memory leak here ? or the NSDate object returned is [autorelease]?

Thanks

Upvotes: 4

Views: 4496

Answers (4)

wei
wei

Reputation: 4727

You will have lots memory leaks.

someDate is a poninter variable and is assigned a block of memory that you allocate, in this case is [[NSDate alloc] init].

However, in the loop you assign your pointer variable to another memory bolck (someDate=[NSDate date])

The memory leak occurs as those memory blocks which have already allocated are unreleased.

Upvotes: 0

Vivek Gajbe
Vivek Gajbe

Reputation: 411

This object-ownership scheme is implemented through a reference-counting system that internally tracks how many owners each object has. When you claim ownership of an object, you increase it’s reference count, and when you’re done with the object, you decrease its reference count. While its reference count is greater than zero, an object is guaranteed to exist, but as soon as the count reaches zero, the operating system is allowed to destroy it.

http://rypress.com/tutorials/objective-c/memory-management

But in latest xcode it provide ARC (Automatic reference counting).
So It will manage reference count automatically .when class is deallocate it release memory for all object it content within .

Upvotes: 1

deanWombourne
deanWombourne

Reputation: 38475

As @DavidKanarek says, you will have leaks.

There are a number of ways to fix these leaks :

NSDate* someDate;
someDate=[NSDate date];
loop
{ 
   someDate=[NSDate date];
}

or

NSDate* someDate=nil;
someDate=[[NSDate alloc] init];
loop
{ 
   [someDate release];
   someDate=[[NSDate alloc] init];
}

[someDate release];

The first one is easier code to read but the second one keeps your memory usage down as low as possible. If your loop is not too big, use the first. If you're going through the loop thousands of times, I'd use the second.

Sam

Upvotes: 5

David Kanarek
David Kanarek

Reputation: 12613

You will have many memory leaks. Objects are initially retained (not autoreleased) if they are returned by methods that have new, alloc or copy in the name. [NSDate date] would be autoreleased. If you post more substantive code I can give you some help in accomplishing your goal cleanly.

Also have a look at Apple's Memory Management Guide.

Upvotes: 4

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