Question

This is an extremely basic question. When I initialize an object like so…

UIView *view;
if (!view) {
    view = [[UIView alloc] init];
}
// Do something with view

I get no compiler errors, but I notice Xcode doesn’t highlight UIView like it normally does. Am I using a bad practice to initialize?

Answer 1

I see two problems with that code:

1. Objective-C doesn’t guarantee initialization of local variables, so view might be 0, a pointer to something else, or a garbage value.
2. Even if Objecitve-C did initialize the variable for you, it doesn’t make a lot of sense to test its value immediately after declaration.

Are you actually declaring this as an instance variable somewhere else?

As far as highlighting, which “UIView” isn’t highlighted? Both? I’d try reloading the file or restarting Xcode.

To fix the two issues I named, replace that with this code:

UIView *view = [[UIView alloc] init];

That raises another issue: under ARC, your newly allocated view will be deallocated when the variable goes out of scope unless you store it in an instance variable or the framework (e.g. superview) stores it somewhere else.

If you’re using manual retain–release instead of ARC, you’ll leak a UIView every time that method is called.