#-objc

Google Maps iOS SDK recommend to use -ObjC key as one of the Build option in "Other Linker Flags" section. Unfortunately if you already use Parse.com iOS SDK this option makes your project fail. If you will follow instructions and add -ObjC key then you will get something like this error while trying to build Map object:

2015-01-21 20:34:25.030 YourApp[5246:346036] -[NSManagedObject tileCoords]: unrecognized selector sent to instance 0x7b7aeb00 2015-01-21 20:34:25.044 YourApp[5246:346036] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSManagedObject tileCoords]: unrecognized selector sent to instance 0x7b7aeb00'

Sometimes you must add the "-all_load" and "-ObjC" flags to the "Other Linker Flags" key into the Project/Target "Build Settings" section.

But, what mean these flags??

Objective-C only generates one symbol to class, we will force the linker to load the members of the class using the -ObjC flag;

we will also force inclusion of all our objects from a static library by adding the -all_load linker flag.

If you not use these flags, you can obtain some errors like "unrecognized selector", "Unknown class myclass in Interface Builder file" or other strange exceptions.

That's all!