Question

What is the difference between the following ways of defining variables?

@interface MyClass: NSObject
{
    NSString *string;
}

@property (nonatomic, strong) NSString *string;

vs.

@interface MyClass: NSObject

@property (nonatomic, strong) NSString *string;

I know that @property takes care of setter and getter (in conjunction with @synthesize) and I know that both ways work fine.
I also know that the latter way does not work for NSArray, NSDictionary. But it works for IBOutlets linked to IB.

Does it have anything with alloc/init? or maybe there is a concept that I am missing totally?

Thanks.

Answer 1

The compiler will automatically create the NSString *string; ivar for you. There is no difference under the latest SDK.

I’ve never ran into issues with NSDictionary not being backed by an explicit ivar.

Update:

Here is the docs on declared properties.

http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/ObjectiveC/Chapters/ocProperties.html