Memory management: manual retain/release or accessor methods?

Question

What is the best approach in terms of:

• security and control of leaks?
• performance?
• visibility outer the class?

First: keeping control of each variable

if (objectProperty_ != anObject) {
    [objectProperty_ release];
    objectProperty_ = [anObject retain];
}

Second: declaring properties and using the accessors and letting the system do the work

@property (nonatomic, readwrite, retain) NSObject *objectProperty;
...
@synthesize objectProperty = objectProperty_;
...
self.objectProperty = anObject;

Thank you.

Answer 1

The approach that is most likely to preserve your sanity is to use Apple-written accessors when you can, and write your own when you must.

The accessor method call does add a slight amount of time; I timed this on my iPad, and I think it was about 10^-7 seconds. This should be true regardless of whether you write the method yourself or use Apple's. In all but the most extreme situations, that is unlikely to matter.

Answer 2

Use properties wherever possible.

1. They save you having to write lots of boilerplate accessor methods. In the days before properties, probably every Cocoa programmer had a pair of macros that they used to define accessors.
2. @property automatically documents the semantics of the accessor. For instance in your example, I can see from the interface that objectProperty retains its value, rather than assigns it or copies it.

Point 2 even holds when you declare properties but define your own accessors.

Answer 3

Less code means less bugs, so just use property to get-set if you have to declare read-write property for public access.