Question

I need to concatenate some strings.

NSString * sportName = [[NSString alloc ]initWithString:@""];
sportName = [sportName stringByAppendingString:[someObject getString]];
// can be more stringByAppendingString
...
[sportName release];

But something strange for me give the ‘build and analyze’ command:

on string:

sportName = [sportName stringByAppendingString:[someObject getString]]; 

the error:
Method returns an Objective-C object with a +0 retain count (non-owning reference)

on string:

[sportName release];

the error:
Incorrect decrement of the reference count of an object that is not owned at this point by the caller

I am using it for filling my TableView and it is crashed after loading :(.

Answer 1

NSString * sportName = [[NSString alloc ]initWithString:@""];
sportName = [sportName stringByAppendingString:[someObject getString]];

In 2nd line you are getting a new string which is assigned back to spotName. So the alloced string in first line is leaked. I don’t understand why you need to append in an empty string. Appending to @"" is practically of no effect. And if you have some non-empty string then you can create that as autoreleased string instead of alloc. Like this:

// create an autoreleased string
NSString * sportName = @"my_string";
// this will return a new string which is also autoreleased
sportName = [sportName stringByAppendingString:[someObject getString]];
// all subsequent call to stringByAppendingString will return autoreleased string
//so no need to release spotName

And if you need to retain spotName then you can retain that or use a property.