Lazy loading of PhotoLibrary Images - objective-c

Question

i found an issue with Photo Library Images. It not displaying first time in my View,Image View is blank while loading first time.
Because i found Asset Library block working on another thread.After reloading my View ,I can see all the Images. However first time the Image Views are Blank.
can any one tell me a good way to deal with the problem
It working with Bundle Images.
also some times console shows that
app is crashing due to Program received signal: “0”. Data Formatters temporarily unavailable, will re-try after a 'continue'. (Unknown error loading shared library "/Developer/usr/lib/libXcodeDebuggerSupport.dylib")
My Code:
for (int j = 0; j<9; j++)
{
//allocating View
UIView *smallView = [[UIView alloc] initWithFrame:CGRectMake(xCordImage, yCordImage, 200, 190)];
// allocating ImageView
imageViewTopic = [[[UIImageView alloc] init] autorelease];
typedef void (^ALAssetsLibraryAssetForURLResultBlock)(ALAsset *asset);
typedef void (^ALAssetsLibraryAccessFailureBlock)(NSError *error);
ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset)
{
ALAssetRepresentation *rep = [myasset defaultRepresentation];
CGImageRef iref = [rep fullResolutionImage];
UIImage *images;
if (iref) {
images = [UIImage imageWithCGImage:iref];
}
else {
images = [UIImage imageNamed:#"Nofile.png"];
}
imageViewTopic .image = images ;
};
ALAssetsLibraryAccessFailureBlock failureblock = ^(NSError *myerror)
{
imageViewTopic .image = [UIImage imageNamed:#"Nofile.png"];
NSLog(#"booya, cant get image - %#",[myerror localizedDescription]);
};
NSString *string ;
MyClass *obj = [imageFileNameArray objectAtIndex:j];
**//obj.fileName contains ALAsset URL of a Image**
string = obj.fileName;
NSURL *asseturl = [NSURL URLWithString:string];
ALAssetsLibrary* assetslibrary = [[[ALAssetsLibrary alloc] init] autorelease];
[assetslibrary assetForURL:asseturl resultBlock:resultblock
failureBlock:failureblock];
imageViewTopic.userInteractionEnabled = YES;
imageViewTopic.frame = CGRectMake(0,0, 200, 150);
[currentView addSubview:scroller];
**// adding the imageView to View**
[smallView addSubview:imageViewTopic];
[myView addSubview:smallView];
[scroller addSubview:myView];
}

Answer 1

I am using this method to show images in scroll view with lazy loading. It works well.
First initialize the value of j1. And data is the image data coming from loop from an array.
dispatch_async(dispatch_get_global_queue(0,0), ^{
NSData * data = [[NSData alloc] initWithContentsOfURL:url];
if ( data == nil )
return;
dispatch_async(dispatch_get_main_queue(), ^{
__block int j1=_j;
// WARNING: is the cell still using the same data by this point??
// NSURL *url = [NSURL URLWithString: imageName];
UIImage *image = [UIImage imageWithData: data]; //image.size.height
image1=[[UIImageView alloc] initWithFrame:CGRectMake(j1,10,image.size.width,image.size.height)];
image1.image=image;
CALayer *layer = [image1 layer];
[layer setMasksToBounds:YES];
[layer setCornerRadius:0.0]; //note that when radius is 0, the border is a rectangle
[layer setBorderWidth:3.0];
[layer setBorderColor:[[UIColor whiteColor] CGColor]];
[portfolio_scroll addSubview:image1];
});
});
_j = _j+ 320;