ObjScopeGuard

Purpose:

• Tiny library intended for adding scope guard support to Objective-C projects. A scope guard is a block of code that is run when the guard goes out of scope.
• This functionality is useful for cleanly specifying resource cleanup, logic that must always be applied before returning, logging, etc. in a more declarative manner.

Requirements:

• Xcode 4.3+
• Clang compiler
• Automatic Reference Counting (ARC) enabled

Example:

- (void)doComplicatedStuffWithCoreData {
    [self.managedObjectContent lock];
     ON_SCOPE_EXIT(^{
         // Unlock the context no matter how we return from method
         [self.managedObjectContext unlock];
     });
	 
     // do complicated stuff with many return points
	 // ...
}

- (void)allocateMemoryAndDoStuff {
    char *buffer = (char *)malloc(sizeof(int) * 1000);
    
    ON_SCOPE_EXIT(^{
		// Make sure buffer is always freed
        free(buffer);
    });
	
	// do complicated stuff with buffer
	// ...
}

- (void)useCoreFoundation {
    CFMutableAttributedStringRef attrString = CFAttributedStringCreateMutable(kCFAllocatorDefault, 0);
	
    MAKE_GUARD(^{
		// Make sure attributed string is always released
		CFRelease(attrString);
	});
	
	// use attributed string
	// ...
}

Usage:

• You need ADScopeGuard.h and ADScopeGuard.m present in your project, either as source or as some form of library.
• MAKE_GUARD(void_block) and ON_SCOPE_EXIT(void_block) are used to create scope guards. The void_block parameter is well ... a void block.

Notes:

• If Objective-C++ is being used, use Boost ScopeExit or something else instead.

Feedback:

• Allen Ding (@alding)