CODEWITHSUNDEEP
objective-c
Curnelious
Curnelious

Reputation: 1

NSString as argument between multiple classes

I am sending NSStrings many times, between classes, and i think i am loosing them.

lets say i have : classA ,classB, classC

classA having instance of classB(allocated) and he is calling function in classB, the function in B:

-(NSMutableData*)setProtocolDataForString:(NSString*)data WithCommand:(int)comm
{ //here i can see and log the string 'data', but i am sending him to classC from here
  [classCInstance send:data];
}

classA call that function with : ..setProtocolDataForString:@"ran"];

As i wrote inside, i can see that classB get the string,but after he pass him to another classC ,i think it is being lost. How exactly functions save/retain the value of NS arguments they get ? How would i do it right so this string can be passed between infinite classes and not freed?

**dont know if its important,but classA/B dont use ARC, but classC does

Upvotes: 0

Views: 65

Answers (3)

Ganapathy
Ganapathy

Reputation: 4614

You have to retain the string because class A and B are not ARC enabled.

-(NSMutableData*)setProtocolDataForString:(NSString*)data WithCommand:(int)comm
{ //here I can see and log the string 'data', but I am sending him to classC from here
   [data retain];
  [classCInstance send:data];
}

Upvotes: 0

Tsimtsum
Tsimtsum

Reputation: 1021

Either allocate or retain NSString object before pass it to class method.

Upvotes: 0

t6d
t6d

Reputation: 2623

Class B needs to have it's own copy of the string it is passing on to class C. Since NSString instances are considered to be value objects you do not simply retain a string, but create a copy instead.

NSString newString = [aString copy]; in this scenario aString can safely be released since you already have a copy with its very own retain count which is not going to be released.

Don't forget to release / auto-release your copy. This is not automatically done for you. If you forget this, your application will leak memory.

The following code should work for you:

[classCInstance send:[[data copy] autorelease]];

Upvotes: 3

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