Initializing from an array of property pointers - ios

Question

I'm trying to write a shortcut for initializing my custom UIView's properties, rather than write out each one line by line, but unfortunately it's not working the way I expected.
// .h file
#property (nonatomic, strong) UIView *view1;
#property (nonatomic, strong) UIView *view2;
#property (nonatomic, strong) UIView *view3;
#property (nonatomic, strong) UIView *view4;
// .m file
UIView *views[] = { self.view1, self.view2, self.view3, self.view4 };
for ( int i = 0; i < sizeof(views) / sizeof(views[0]); i++ ) {
views[i] = [[UIView alloc] initWithFrame:self.frame];
}
NSLog( #"%#", self.view1 ); // prints null
Is this just not allowed with C-style arrays?

Answer 1

Your initialization of views[] looks fine, but as soon as you do
views[i] = ...
you are merely overwriting the contents of the array. You are, however, not initializing self.view1, self.view2, etc. Try
NSLog(#"%#", views[0]);
to see what I mean.
I would not do it like follows, but you could probably do (untested):
UIView **views[] = { &self.view1, &self.view2, &self.view3, &self.view4 };
for (int i = 0; i < (sizeof(views) / sizeof(views[0]); ++i)
{
*views[i] = [[UIView alloc] initWithFrame: self.frame];
}
NSLog(#"%#", self.view1);
I would rather initialize them one by one, without the array. I don't see any advantage in using an array and a loop.

Answer 2

You are just changing the pointer inside the array, the self.view1 pointer will still point to nil.
You could have an array of views as property:
#property(nonatomic,strong) UIView **views;
Or maybe you can use Key Value Coding like
for(int i=1;i<5;i++){
NSString* key = [NSString stringWithFormat:#"view%i",i];
UIView *view = //initialize view
[self setValue:view forKey:key];
}

Answer 3

Calling e.g. self.view1 at the beginning will give you nil before you have initialized it. So the line
UIView *views[] = { self.view1, self.view2, self.view3, self.view4 };
is effectively creating an array of 4 nils.
Inserting the new instances of UIView to the array afterwards has no effect on the properties. In fact, a property is only a pair of selectors (e.g. view1 and setView1:) and by itself cannot be used reliably with C-style pointers.
You could use the backing ivars with an array of UIView ** pointers, but you're most likely better off rethinking the whole approach.