If you want access to properites and methods in your Objectice-C tests try this.

#import "IAPClientImplementationTestBase.h"

@interface IAPClientImplementation()
@property (nonatomic, readwrite) NSUInteger currentRequestID;
@end

@interface IAPClientImplementationTest : IAPClientImplementationTestBase
@end

@implementation IAPClientImplementationTest

- (void)testRequestIdIncrements {
    XCTAssertEqual(0, [self.client currentRequestID]);
}

@end

Redefine the interface in your test class and re-expose the properties and methods there.