A few "String Issue Format" warnings in JSONKit.m after upgrading to PhoneGap 2.0 on iOS

We just upgraded to PhoneGap / Cordova 2.0 on iOS, but we see some warnings in JSONKit.m.

There are two classes of warnings: (1) “Line formatting” and (2) “Semantic problem”.

Here is an example of "Format string problems":

/Users/macuser/Documents/CordovaLib/Classes/JSON/JSONKit.m:745:180: Format specifies type 'unsigned long' but the argument has type 'NSUInteger' (aka 'unsigned int')

Here is an example of the "Semantic Problem":

/Users/macuser/Documents/CordovaLib/Classes/JSON/JSONKit.m:2600:11: Direct access to objective-c isa is deprecated in favor of object_setClass() and object_getClass()

We are on Lion, Xcode 4.4.

Any clues why this warning is happening now, when aren't they earlier?

Thank!