UIImage** for change dynamically value of UIImageView - ios

Question

i have try to create an Image Controller for store image and reuse it when need during one instance of application, this is my class
[Nota: the method controllaDictionary search the key of the image if is was just used (explain on detail above)]
-(void)imageContentUrl:(NSString*)imageURL andImage:(UIImage**)image{
NSLog(#"Stampa Immagine Contente URL: %#",imageURL);
NSString* imageName = [[imageURL componentsSeparatedByString:#"/"] lastObject];
if([self controllaDictionary:imageName]){
NSLog(#"||| IMMAGES ---------> Image Exixt in Dictionary");
UIImage* imageInDict = [self controllaDictionary:imageName];
image = &imageInDict;
return;
}else{
UIImage* imageFile = nil;
if([imageName isEqualToString:#""] || imageName == nil){
NSLog(#"||| IMMAGES ------- Null Link");
image = nil;
}
if([[NSFileManager defaultManager] fileExistsAtPath:[NSString stringWithFormat:#"%#/%#",_imageDirectory,imageName]]){
NSLog(#"||| IMMAGES ------- Exist in Folder: %#",[NSString stringWithFormat:#"%#/%#",_imageDirectory,imageName]);
imageFile = [UIImage imageWithContentsOfFile:[NSString stringWithFormat:#"%#/%#",_imageDirectory,imageName]];
image = &imageFile;
[self.imageDict setValue:imageFile forKey:imageName];
return;
}else{
NSLog(#"||| IMMAGINI ------- Miss, Start Download at URL: %#",imageURL);
[self downloadImageAtUrl:imageURL andImagePointer:image withHendlerBlock:^(NSError *error, UIImage *image, NSString *urlImage,UIImage** doubleImagePointer) {
if (!error) {
NSLog(#"Stampa Double Pointer IMG -> %#",image);
doubleImagePointer = ℑ
[self saveImage:image andName:imageName];
[self.imageDict setValue:image forKey:imageName];
}else{
NSLog(#"Stampa Errore: %#",error);
}
}];
}
}
}
-(void)downloadImageAtUrl:(NSString*)urlImage andImagePointer:(UIImage**)image withHendlerBlock:(void(^)(NSError* error,UIImage* imageDownloaded,NSString* urlImage,UIImage** doubleImagePointer))dowloadImageBlock{
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(queue, ^{
UIImage* downloadImg = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:urlImage]]];
NSError* error = nil;
if (downloadImg) {
NSLog(#"Immagine Acquisita");
}else{
NSLog(#"Errore Download Compilazione Errore");
error = [NSError errorWithDomain:DownloadErrorDomain code:0 userInfo:#{DownloadErrorDomain: #"Errore nel download dell'immagine, non si hanno a disposizione ulteriori strumenti per comprenderne la natura. Effettuare un ceck della URL"}];
}
dowloadImageBlock(error,downloadImg,urlImage,image);
});
}
#end
ok after this i explain you how wath i have to do:
QUickly is a singleton instance that search in a specific Folder if there is a Image.
Yes set image and done, No start dowload then set and done.
I have see that this method is powerfull for memory management because i create a NSMutabeDictionary with the name of image like a key and the UIImage for value so i use only one pointer for multiple instance of same image [then i allocate in memory the image only first time].
-(void)imageContentUrl:imageURL andImage:(UIImage**)image
this method search in the dir if file exist and set the image-> now i would operate like sometime run NSError so i pass to this method an UIImage**
like this
UIImage* image = nil;
[[GestoreImmagini instance] imageContentUrl:#"URL/Immage/For/Download.jpg" andImage:&image];
[self.imageEvent setImage:image];
the in async i set the image.
this is my Idea but the image are downloaded and set (and if i log, are printed on console) but self.imageEvent don't show the image... Some one can help me?
#Edit After Cy-4AH Answer
Correct!! Is my fault... after C++ i have pass more time to work without pointer and i have forgot somting...
tnx but now the second portion of the code after dowload and the return from the block the image was not set... [with correction of *]
[self downloadImageAtUrl:imageURL andImagePointer:image withHendlerBlock:^(NSError *error, UIImage *image, NSString *urlImage,UIImage** doubleImagePointer) {
if (!error) {
NSLog(#"Stampa Double Pointer IMG -> %#",image);
*doubleImagePointer = image;
[self saveImage:image andName:imageName];
[self.imageDict setValue:image forKey:imageName];
}else{
NSLog(#"Stampa Errore: %#",error);
}
}];
why? on theory the pointer is the same...
#Edit After DEBUG
i have found problem here at the log 2.0 , 2.1 and 2.2 the image print (null) and this i correct because i not have set it but in 2.3 i have a crash for BAD_ACCESS like miss all References. and same happens when i print it in the dowloadImageBlock().
-(void)downloadImageAtUrl:(NSString*)urlImage andImagePointer:(UIImage**)image withHendlerBlock:(void(^)(NSError* error,UIImage* imageDownloaded,NSString* urlImage,UIImage** doubleImagePointer))dowloadImageBlock{
NSLog(#" 2.0 - ||| ----- -------- -----------> %#",*image);
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
NSLog(#" 2.1 - ||| ----- -------- -----------> %#",*image);
dispatch_async(queue, ^{
NSLog(#" 2.2 - ||| ----- -------- -----------> %#",*image);
UIImage* downloadImg = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:urlImage]]];
NSError* error = nil;
if (downloadImg) {
NSLog(#"Immagine Acquisita");
}else{
NSLog(#"Errore Download Compilazione Errore");
error = [NSError errorWithDomain:DownloadErrorDomain code:0 userInfo:#{DownloadErrorDomain: #"Errore nel download dell'immagine, non si hanno a disposizione ulteriori strumenti per comprenderne la natura. Effettuare un ceck della URL"}];
}
NSLog(#" 2.3 - ||| ----- -------- -----------> %#",*image);
dowloadImageBlock(error,downloadImg,urlImage,image);
});
}

Answer 1

You have missanderstanding in working with pointers.
It's should be:
*image = imageInDict;
Also you download image asynchroniously, and yours variable located in function call stack is already destroyed, when you try assign value to it. You should better use UIImageView* or some other objective-c class that have UIImage* in properties instead UIImage**