CODEWITHSUNDEEP
objective-c
kientux
kientux

Reputation: 1792

Objective-C creating object first then assign to property

Sorry if the title is confused but I can't find a way to express my question.

I see many Objective-C example codes and they usually use this:

    Clazz *clazz = [[Clazz alloc] init];
    self.clazz = clazz;

instead of:

    self.clazz = [[Clazz alloc] init];

Does the first approach have any advantage over the second one?

Upvotes: 3

Views: 74

Answers (2)

JaredH
JaredH

Reputation: 2398

This is usually just a stylistic preference. It's possible that you want to declare Class *clazz = [[Clazz alloc] init]; in a separate line so that you call methods on it, or set properties on the class, before you actually assign it to the property, especially if you have a custom setter for that class.

eg:

@interface ThisIsAClass ()

@property (nonatomic, strong) Clazz *clazz;

@end


@implementation ThisIsAClass

- (instancetype) init {
    if (self = [super init]) {
        Clazz *clazz = [[Clazz alloc] init];
        clazz.widgets = @[@"onesie", @"twosie"];
        self.clazz = clazz;
    }
    return self;
}

- (void)clazz:(Clazz *)newClazz {
     // Make sure we're assigning valid values to this property
     NSAssert(newClazz.widgets.count > 0, @"Widgets count must be > 0!");
     _clazz = newClazz;
}

@end

Upvotes: 2

rob mayoff
rob mayoff

Reputation: 385720

There's no advantage if that's all it does. If the code uses clazz further, then accessing a local variable saves the nanoseconds required to call the self.clazz getter, and avoids the getter entirely which could matter if the getter does anything weird.

Upvotes: 5

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