I have some trouble with compare two ALAssets object. I have two NSMutableArray: selectedImages and mutableAssets. I store there ALAssets object. But when i want to compare this assets it doesnt work for isEqual or containsObject method, only when i compare it by their url it works:
ALAsset *asset1 = [self.mutableAssets objectAtIndex:0];
ALAsset *asset2 = [self.selectedImages objectAtIndex:0];
NSLog(@"%@", asset1);
NSLog(@"%@", asset2);
if([self.selectedImages containsObject:[self.mutableAssets objectAtIndex:0]]) {
NSLog(@"the same1");
}
if([asset1 isEqual:asset2]) {
NSLog(@"the sames2");
}
if([asset1.defaultRepresentation.url isEqual:asset2.defaultRepresentation.url]) {
NSLog(@"the same3");
}
Gives only this line:
ALAsset - Type:Photo, URLs:assets-library://asset/asset.JPG?id=E8947286-22E2-42E4-A904-14D940A387B3&ext=JPG
ALAsset - Type:Photo, URLs:assets-library://asset/asset.JPG?id=E8947286-22E2-42E4-A904-14D940A387B3&ext=JPG
the same3
Why it happens?
seems like Assets don't implement isEqual:
I would not check the defaultRep's URL though... two different assets may have the same defaultRep in a way
I'd go with the ALAssetPropertyAssetURL for iOS 6+
or ALAssetPropertyURLs for ios4&5
--- you could wrap this in a category even!
@interface ALAsset (isEqual)
- (NSURL*)defaultURL;
@end
@implementation ALAsset (isEqual)
- (NSURL*)defaultURL {
if([[[UIDevice currentDevice] systemVersion] floatValue]>=6.0)
{
return [self valueForKey: ALAssetPropertyAssetURL];
}
else
{
return self.defaultRepresentation.url;
}
}
- (BOOL)isEqual:(id)obj {
if(![obj isKindOfClass:[ALAsset class]])
return NO;
NSURL *u1 = [self defaultURL];
NSURL *u2 = [obj defaultURL];
return ([u1 isEqual:u2]);
}
for iOS 4 and 5 and 6 and up
containsObject:
is determines whether anObject is present in the array by sending an isEqual: message to each of the array's objects (and passing anObject as the parameter to each isEqual: message).
isEqual:
is inspect whether two objects are the same. If two objects are equal, they must have the same hash
value. hash
means a table address in a hash table structure.
so, if not containsObject also not isEqual. Derive the results if you want to your ALAsset override isEqual
.
NSURL, isEqual
is two NSURLs are considered equal if and only if they return identical values for both baseURL and relativeString.
if([[[asset1 defaultRepresentation].url absoluteString] isEqualToString:[[asset2 defaultRepresentation].url absoluteString]])
{
}
else
{
}
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