iOS - Bad Access when calling ALAssetsLibrary several times - ios

Question

When a user uploads a picture from the iPhone gallery, I extract the location using ALAssetsLibrary:
ALAssetsLibrary* assetslibrary = [[ALAssetsLibrary alloc] init];
[assetslibrary assetForURL:urlPhoto
resultBlock:^(ALAsset *asset) {
CLLocation *location = [asset valueForProperty:ALAssetPropertyLocation];
} failureBlock:^(NSError *error) {
NSLog(#"Can not get asset - %#",[error localizedDescription]);
}];
However, if the user uploads a picture and then returns to the upload screen and upload another, after three or four uploads the app crashes on EXC_BAD_ACCESS, when running the assetForURL:resultBlock:failureBlock: method.
I guess it happens since the assetForURL:resultBlock:failureBlock: runs async and the ALAssetsLibrary is released for some reason, though it cannot run simultaneously the way I've built the app.
How can I prevent it from crashing?
EDIT
Although the crash was always at this point (due to the earlier dismiss), the error occurred because of a UITableView that was deallocated earlier, but at this point referred to its delegate/datasource.
the fix was adding:
- (void) dealloc
{
myTableView.dataSource = nil;
myTableView.delegate = nil;
}
at the end of the UIViewController that had the TableView.

Answer 1

Just change your object to property .
interface:
#property (nonatomic, strong) ALAssetsLibrary* assetslibrary;
Than call implementation:
if (self.assetslibrary == nil) {
self.assetslibrary = [[ALAssetsLibrary alloc] init];
}
[self.assetslibrary assetForURL:urlPhoto
resultBlock:^(ALAsset *asset) {
CLLocation *location = [asset valueForProperty:ALAssetPropertyLocation];
} failureBlock:^(NSError *error) {
NSLog(#"Can not get asset - %#",[error localizedDescription]);
}];