My applicationDidFinishLaunching crashes when I alloc init a NSMetaDataQuery.... Help please - ios5

Question

I am updating my app to use iCloud and want my iOS deployment target to remain 3.2. I am conditionally shielding any iOS 5 calls to prevent any back level versions from crashing. My applicationDidFinishLaunching looks like...
- (void)applicationDidFinishLaunching:(UIApplication *)application {
NSLog(#"Launching Began...");
navigationController = [[UINavigationController alloc] init];
navigationController.navigationBar.barStyle = UIBarStyleBlack;
[window addSubview:navigationController.view];
[window makeKeyAndVisible];
// Getting the documentsPath.
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsPath = [paths objectAtIndex:0];
// Setting up the mainCarList
//unarchive the saved carlist
NSString *archivePathFilename = [documentsPath stringByAppendingString:#"/carlist.archive"];
self.mainCarList = nil;
self.mainCarList = [[NSKeyedUnarchiver unarchiveObjectWithFile:archivePathFilename] retain];
//if OS version => 5.0 then
NSString *reqSysVer = #"5.0";
NSString *currSysVer = [[UIDevice currentDevice] systemVersion];
if ([currSysVer compare:reqSysVer options:NSNumericSearch] != NSOrderedAscending) {
NSLog(#"in ApplicationDidFinishLaunching iOS version > 5.0");
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(carListDocumentStateChanged) name:#"UIDocumentStateChangedNotification" object:Nil];
NSString *carListDocumentURLString = [documentsPath stringByAppendingString:#"/mainCarListDocument.CLD"];
self.mainCarListDocumentURL = [NSURL fileURLWithPath:carListDocumentURLString]; //sets the local save location only in this property
Class cls = NSClassFromString (#"NSMetadataQuery");
if (cls) {
NSMetadataQuery *query;
query = [[NSMetadataQuery alloc] init]; // <------- This crashes when running v4.3 iPhone sim.
/*
NSMetadataQuery *query = [[NSMetadataQuery alloc] init];
[self setDocumentMetaDataQuery:query];
[query setSearchScopes:[NSArray arrayWithObject:NSMetadataQueryUbiquitousDataScope]];
[query setPredicate:[NSPredicate predicateWithFormat:#"%K == %#", NSMetadataItemFSNameKey, #"mainCarListDocument.CLD"]];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(queryDidFinishGathering) name:NSMetadataQueryDidFinishGatheringNotification object:Nil];
BOOL didStart = NO;
didStart = [query startQuery];
if (didStart) {
NSLog(#"documentMetaDataQuery started");
}
else {
NSLog(#"error starting documentMetaDataQuery");
}
*/
[query release];
}
...
I think something is going on at compile time since the "Launching Began" log is not posted. The conditional block works correctly. If I comment out the query's alloc init, then the block gets ran only if iOS 5 is running. Any ideas?

Answer 1

Replace the following code:
NSMetadataQuery *query;
query = [[NSMetadataQuery alloc] init];
By this code:
id query;
query = [[cls alloc] init];

Answer 2

You have to use cls instead of NSMetadataQuery.