Correct syntax for Objective-C init method

Why doesn't this common property initialization scheme risk failure when the synthesized setter tries to release the undefined myArray object? Or are property objects automatically initialized to nil and I don't need to be doing this at all?

@interface myClass : NSObject {
    NSArray* myArray;
}
@property (nonatomic, retain) NSArray* myArray;
@end

@implementation myClass
@synthesize myArray;
-(id)init {
    if ( self = [super init] ) {
        self.myArray = nil;
    }
    return self;
}

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