NSMutableArray empty after created in init (with code)

Question

@property (nonatomic, strong) NSMutableArray *authorMutableArray;

- (id)init {
 self = [super init];
 if (self) {
 self.authorMutableArray = [[NSMutableArray alloc] initWithObjects:@"First Row", @"Second Row", nil];
 for (NSString *string in authorMutableArray) {
 NSLog(@"String: %@", string);
 }
 NSLog(@"Init in Add Model with Author count:%i", [authorMutableArray count]);
 }
}

An example of accessing the property. The NSLog always shows the count as 0.

 - (UITableViewCellEditingStyle)tableView:(UITableView *)tableView editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath
{
 if (indexPath.section == 0) { 
 if (indexPath.row == [self.addModel.authorMutableArray count] - 1 ) {
 NSLog(@"count of %i", [self.addModel.authorMutableArray count]);
 return UITableViewCellEditingStyleInsert;
 }
 else {
 return UITableViewCellEditingStyleDelete;
 }
 }
 else {
 return UITableViewCellEditingStyleNone;
 }
}

The array I'm creating in init is not keeping its values past this method. Any reason why? The for loop will show both objects in the array. If I try to ask this after the init method is called, the array is empty.

Updated: Thank you everyone for your time and eyes. I had forgotten to return self in the init method.

• Warren Burton: How do you declare the authormutablearray property
• wes: It's regular synthesized property.
• Itai Ferber: @WDyson What Warren means is, what specifiers are you using? strong, weak, assign? Also, how are you accessing the array afterwards? Can you show us the code for that?
• wes: I'll update the OP, it's strong.
• Michael Dautermann: In your editingStyleForRowAtIndexPath method, check to see if addModel is not nil, too.

Answer 1

Shouldn't the init method return self ?

• wes: Yes, it did. I have 4 NSString properties I was creating in the same init method, I just excluded them for this example. They all worked fine. Why is it the array was the only one not to keep its data?

Answer 2

In your class' interface file(.h file) declare like this:

@interface Your_Class_Name : UIViewController {
 NSMutableArray *authorMutableArray;
}
@property (nonatomic, strong) NSMutableArray *authorMutableArray;
//i dont know why you prefered strong, chose retain and try again please

• jscs: strong is the equivalent to retain under ARC. They have equivalent semantics in their respective memory management systems. It's also unecessary to declare the ivar separately; it's created by @synthesize.
• wes: @lulius, which would you use for the array, strong or retain?
• jscs: copy, actually, for a class that has a mutable counterpart, but the choice between strong and retain simply depends on whether you're using ARC or not.
• wes: Strong for ARC, retain otherwise? And what do you mean by mutable counterpart? I just want to make sure I completely understand.
• jscs: @WDy Yes, strong under ARC. Mutable counterpart meaning NSArray/NSMutableArray, NSString/NSMutableString, NSIndexSet/NSMutableIndexSet, and so on. If a mutable instance is passed in to your setter, it can be changed by the original owner unless you take a copy, which may have surprising results. There are SO questions around that go into more depth about that.

Answer 3

We aren't dealing with C++ or Java here, the -init method of an object MUST return a value.

This quirk actually allows for some pretty interesting stuff, e.x. the following:

-(id) init {
 NSLog(@"Creating new instance of singleton object...");
 #if __has_feature(objc-arc)
 self = singleton_instance;
 #else
 [self release];
 self = [singleton_instance retain];
 #endif 
 return self;
}

It also allows for class 'posing' of a sort, allowing you to track exactly when an object of a particular class is initialized (that is too deep of a topic for this answer).