Does NSString componentsSeparatedByString: return autoreleased array?

In the following method, I'm unsure of why releasing one of the arrays leads to an exception. The only reason that I could see, would be if componentsSeparatedByString returns an autoreleased array, but I can't see that the documentation mentions that it do.

-(void)addRow:(NSString *)stringWithNumbers;
{

    NSArray *numbers = [stringWithNumbers componentsSeparatedByString:@" "];
    NSMutableArray *row = [[NSMutableArray alloc] initWithCapacity:[numbers count]];
    for (NSString *number in numbers) {
        Number *n = [[Number alloc] initWithNumber:number];
        [row addObject:n];
        [n release]开发者_如何转开发;
    }
    [rows addObject:row];
    [row release];
//    [numbers release];  <-- leads to exception
}

Can anyone confirm if the array is autoreleased? If so, how can I know/why should I have known?

Is it possible to check if any one instance of an object is autoreleased or not by code?

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Yes, because the name of the method:

• does not start with new
• does not start with alloc
• is not retain
• does not contain copy

This is commonly known as the "NARC" rule, and is fully explained here: http://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/MemoryMgmt/Articles/mmObjectOwnership.html#//apple_ref/doc/uid/20000043-SW1

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unless you specifically allocate memory, a system method will give you back an autoreleased method.

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By convention all methods with init or copy in their names return non-autoreleased objects.