Question

When I run this code

NSString *string = [NSString stringWithFormat:@"http://makrr.com/*****/****/*****/****/%@.mp3", [data objectForKey:@"location"]];`  

Im getting a EXC_BAD_ACCESS. [data objectForKey:@”Location”] is a NSCFString.

Answer 1

I’m not sure where the EXC_BAD_ACCESS is coming from, but the compiler is reading [data objectForKey:@"Location"] as an NSCFString since NSString is a class cluster, along with other Foundation types such as NSNumber and NSArray:

Class clusters are a design pattern that the Foundation framework
makes extensive use of. Class clusters group a number of private,
concrete subclasses under a public, abstract superclass. The grouping
of classes in this way simplifies the publicly visible architecture of
an object-oriented framework without reducing its functional richness.
Class clusters are based on the Abstract Factory design pattern
discussed in “Cocoa Design Patterns.”

Most likely, [data objectForKey:@"Location"] has been released one too many times and has been deallocated. This could case an error EXC_BAD_ACCESS. You should check your memory management carefully to see that it is not being autoreleased (or manually released).