A test to ensure that NSCache doesn't give up after multiple memory warnings.

NSCacheTest.m

- (void)testThatNSCacheDoesntGiveUp
{
  NSCache *cache = [[NSCache alloc] init];
  for (NSInteger i = 0; i < 5; i++) {
    // Add a couple entries for good measure
    [cache setObject:(id)kCFNull forKey:[NSUUID UUID]];
    [cache setObject:(id)kCFNull forKey:[NSUUID UUID]];

    [self expectationForNotification:UIApplicationDidReceiveMemoryWarningNotification object:nil handler:nil];
    NSLog(@"Awaiting memory warning…");
    [self waitForExpectationsWithTimeout:30 handler:nil];
  }

  // Now that we've sent two memory warnings, ensure the cache still works.
  NSUUID *newKey = [NSUUID UUID];
  [cache setObject:(id)kCFNull forKey:newKey];
  XCTAssertNotNil([cache objectForKey:newKey]);
}