Objective-c – Memory issue of NSString

cocoaobjective c

I have got a problem with NSString.

NSString* str = [[NSString alloc] initWithString:@"Hello world"];

In the code above, do I need to release the object str? According to the rule, this object is created with alloc, so it should be explicitly released with the release method. However, I can't find any memory leaks in Instruments when I don't explicitly release it.
When the NSString is replaced with NSNumber, the memory leaks happen.

Can anyone give me some suggestions? Thanks.

Best Answer

Yes, you do need to release it. Tools such as Instruments, Leaks, ObjectAlloc and friends aren't infallible; also because you've used a constant string to create the instance it is entirely likely that no leak occurs. But nonetheless, if you +alloc an object you should also -release it to make sure that the object doesn't leak, so you do indeed need to release this object.

My usual set of links to Cocoa memory management articles: http://iamleeg.blogspot.com/2008/12/cocoa-memory-management.html

Related Solutions

Objective-c – NSString property: copy or retain

For attributes whose type is an immutable value class that conforms to the NSCopying protocol, you almost always should specify copy in your @property declaration. Specifying retain is something you almost never want in such a situation.

Here's why you want to do that:

NSMutableString *someName = [NSMutableString stringWithString:@"Chris"];

Person *p = [[[Person alloc] init] autorelease];
p.name = someName;

[someName setString:@"Debajit"];

The current value of the Person.name property will be different depending on whether the property is declared retain or copy — it will be @"Debajit" if the property is marked retain, but @"Chris" if the property is marked copy.

Since in almost all cases you want to prevent mutating an object's attributes behind its back, you should mark the properties representing them copy. (And if you write the setter yourself instead of using @synthesize you should remember to actually use copy instead of retain in it.)

Ios – How to convert an NSString value to NSData

NSString* str = @"teststring";
NSData* data = [str dataUsingEncoding:NSUTF8StringEncoding];

Best Answer

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Objective-c – NSString property: copy or retain

Ios – How to convert an NSString value to NSData

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