Chartboost always crashes in iOS5-Collection of common programming errors

I don’t know Chartboost, but the error message indicates that the code makes use of the modern “NSDictionary and NSArray subscripting” feature, e.g.

dict[@"key"] // instead of [dict objectForKey:@"key"]

According to the “Objective-C Feature Availability Index”, NSDictionary and NSArray subscripting requires the iOS 6.0 or later SDK and the LLVM Compiler 4.0. It deploys to iOS 5 and later.

So if you don’t need the iOS 4.3 compatibility, setting the deployment target to iOS 5 and compiling against the iOS 6 SDK should solve the problem. Make sure that “Apple LLVM compiler” and not “LLVM GCC” or similar is set as compiler in the build settings.