I can guess what might be the problem here, because I've done it:
I've found that often when I add init code to loadView, I end up with an infinite stack trace
Don't read self.view in -loadView. Only set it, don't get it.
The self.view property accessor calls -loadView if the view isn't currently loaded. There's your infinite recursion.
The usual way to build the view programmatically in -loadView, as demonstrated in Apple's pre-Interface-Builder examples, is more like this:
UIView *view = [[UIView alloc] init...];
...
[view addSubview:whatever];
[view addSubview:whatever2];
...
self.view = view;
[view release];
And I don't blame you for not using IB. I've stuck with this method for all of Instapaper and find myself much more comfortable with it than dealing with IB's complexities, interface quirks, and unexpected behind-the-scenes behavior.
The last two are identical; "atomic" is the default behavior (note that it is not actually a keyword; it is specified only by the absence of nonatomic
-- atomic
was added as a keyword in recent versions of llvm/clang).
Assuming that you are @synthesizing the method implementations, atomic vs. non-atomic changes the generated code. If you are writing your own setter/getters, atomic/nonatomic/retain/assign/copy are merely advisory. (Note: @synthesize is now the default behavior in recent versions of LLVM. There is also no need to declare instance variables; they will be synthesized automatically, too, and will have an _
prepended to their name to prevent accidental direct access).
With "atomic", the synthesized setter/getter will ensure that a whole value is always returned from the getter or set by the setter, regardless of setter activity on any other thread. That is, if thread A is in the middle of the getter while thread B calls the setter, an actual viable value -- an autoreleased object, most likely -- will be returned to the caller in A.
In nonatomic
, no such guarantees are made. Thus, nonatomic
is considerably faster than "atomic".
What "atomic" does not do is make any guarantees about thread safety. If thread A is calling the getter simultaneously with thread B and C calling the setter with different values, thread A may get any one of the three values returned -- the one prior to any setters being called or either of the values passed into the setters in B and C. Likewise, the object may end up with the value from B or C, no way to tell.
Ensuring data integrity -- one of the primary challenges of multi-threaded programming -- is achieved by other means.
Adding to this:
atomicity
of a single property also cannot guarantee thread safety when multiple dependent properties are in play.
Consider:
@property(atomic, copy) NSString *firstName;
@property(atomic, copy) NSString *lastName;
@property(readonly, atomic, copy) NSString *fullName;
In this case, thread A could be renaming the object by calling setFirstName:
and then calling setLastName:
. In the meantime, thread B may call fullName
in between thread A's two calls and will receive the new first name coupled with the old last name.
To address this, you need a transactional model. I.e. some other kind of synchronization and/or exclusion that allows one to exclude access to fullName
while the dependent properties are being updated.
Best Answer
A push Segue is adding another VC to the navigation stack. This assumes that VC that originates the push is part of the same navigation controller that the VC that is being added to the stack belongs to. Memory management is not an issue with navigation controllers and a deep stack. As long as you are taking care of objects you might be passing from one VC to another, the runtime will take care of the navigation stack. See the image for a visual indication:
A modal Segue is just one VC presenting another VC modally. The VCs don't have to be part of a navigation controller and the VC being presented modally is generally considered to be a "child" of the presenting (parent) VC. The modally presented VC is usually sans any navigation bars or tab bars. The presenting VC is also responsible for dismissing the modal VC it created and presented.
Hope this helps.