- Basic Questions:
- identify basic OO concepts and the keywords Objective-C uses (interface, implementation, property, protocol, etc)
- what is a designated initializer, what is the pattern for the initializers and why ( if (self = [super ...] ) )
- basic memory management topics, like ownership retain/release/autorelease
- what happens if you add your just created object to a mutable array, and you release your object
- what happens if the array is released
- what happens if you remove the object from the array, and you try to use it
- trick: garbage collection on iPhone
- autorelease pool usage
- property declarations ( assign, nonatomic, readonly, retain, copy )
- trick: ask about the nonexistent atomic keyword, what does atomic mean
- ask on how to correctly implement a retaining setter property
- ask about the circular reference problem and delegates being usually saved with assign rather then retain
- what is the difference between the dot notation and using the square brackets
- what happens when we invoke a method on a nil pointer
- difference between nil and Nil
- what is KVO and related theory + methods to use when observing
- does KVO work with ivars too?
- protocols – maybe: main difference between c#/java interface and protocols
- what to do in a situation when a class doesn’t implement a method from a protocol
- what about multiple class inheritance
- what is fast enumeration
- class methods vs instance methods
- visibility of methods
- what is an actual class in Objective-c (struct)
- ask about the isa member
- ask about isKindOfClass isMemberOfClass
- root classes: NSObject, NSProxy
- how does proxy-ing work
- how to fake multiple class inheritance
- id type
- what happens during compilation if we invoke a method on an variable with the type id
- what happens runtime if the method exists
- what happens if the methods doesn’t exist
- pro and cons of using the type id
- what happens here(compile + runtime): NSString *s = [NSNumber numberWithInt:3]; int i = [s intValue];
- what are class categories and the () category
- what is an informal protocol
- what is a delegate, how to create one, and use one
- what is a selector, how to do a perform selector
- how to delay executing a selector
- what to do when the selector has more paramters (NSInvocation>
- how to start a selector on a background thread
- how to start a thread
- what is the first thing to do on a thread (autorelease pool)
- what is a runloop, and one very common place where it is used (timers, nsurlconnection)
- how to download something from the internet
- what is the difference between a synchronous and an asynchronous request
- small task: explain how to download an image from the internet, and show this in an image view – all this after a button is tapped on the view
- what are notifications, how to use them
- what is a memory warning, how do we respond to it
—- A bit more advanced topics —-
- when to use retainCount (never, and why)
- why shouldn’t we invoke instance methods in an initializer and the dealloc
- NSCoding, archiving
- NSCopying, why can’t we simply use our own objects as key in a dictionary, what to do to solve the problem ( and the difference between a shallow and a deep copy)
—- UIKit related —-
- what is a view, and a window
- difference between a view’s bounds and frame
- what is the resolution of the current available devices, difference between points and pixels (starting with iOS4)
- what is the responder chain, becomeFirstResponder
- what do IBOutlet and IBAction mean, what are they preprocessed to
- how do tableviews function
- what about multithreading and UIKit
- what to do when the keyboard appears and hides some parts of the UI that are important
- why should we release the outlets in viewDidUnload
- what is awakeFromNib, what is the difference between a nib and a xib
—- CoreData —-
- what is a context
- what about multi threading and core data usage
- what is an NSManagedObjectId – can we save it for later if the application was stopped
- what types of stores does core data support
- what is lazy loading, how does this relate to core data, situations when this can be handy
- how to ready only a few attributes of an entity
- what is an fetch result controller
- how to synchronize contexts
- how could one simulate an NSManagedObject (i’m thinking of the fact that all the properties are dynamic and not synthesized)
