Question

I am creating subview class that gets information about its frame from its datasource. I would like to create a custom initialization method that takes a object which implements the datasource protocol as an argument. One of the datasource protocol methods, frameSize, has the datasource return a CGrect. My question is if it is possible to set the datasource in a custom initialization before calling [super initWithFrame]? This is what I have:

-(id) initWithDataSource:(id)dataSource
{
self._dataSource=dataSource;
[super initWithFrame:[self._dataSource frameSize];
return self;
}

Its seems counterintuitive to me to set a property before calling the initialization method. Is there a good way to do this, or is it feasible to initialize it with an empty frame and then set the frame later? Thanks in advance

Answer 1

An init method must always assign self = [super initXXX], because the super init method might return a value different from the original self.

But you could call initWithFrame: with a dummy rect first and assign the actual frame after self is initialized:

-(id) initWithDataSource:(id)dataSource
{
    self = [super initWithFrame:CGRectMake(0, 0, 1, 1)];
    if (self) {
        self._dataSource = dataSource;
        self.frame = [self._dataSource frameSize];
    }
    return self;
}