Category: iOS

Strange UIAlertView crash

On iOS8+ presenting an AlertView can lead to a crash: NSInternalInconsistencyException what you cannot really catch. Spending quite some time around this I realized the issue comes when the keyboard is open. Closing the keyboard (endEditing) solves the issue. I also found a good thread about this at stackoverflow  

Strange issues with certificates on iOS

Good to know: in case of HTTPS/SSL/TLS connection iOS devices cache the used certificate. The side effect come along when you create (get) certificate at runtime and try to use them to connect to a server. The first time you get the certificate challenge, but not the second time – at least if you try […]

Blocks in Objective-C

Blocks in Objective-C Quick overview Blocks are the closure pattern implementation in Objective-C. Blocks are objects containing code like a method but blocks are standalone objects (not belonging to a specific class/instance) encapsulating and capturing the code and variables enclosed in the beginning and closing brackets. You declare a block type or variable this way: returnType […]

Allocate Swift objects from Objective-C

Using mixed projects you can face with several challenging situations. One of them is the allocation of Swift objects in ObjC code. The general problem that Swift objects doesn’t have an alloc method which is used to allocate the memory in ObjC ([[SwiftClass alloc] init]). To access the Swift object you should prefix it with @objc – or subclass […]

Navigating back and forth among Viewcontrollers in Storyboard

In the old days if you wanted to present a ViewController you should call presentModal.. or push… in the code.  The problem with this approach is that if you want to modify the presentation you should change the code. To separate this Apple found out the Storyboard – all your ViewControllers in one place. Visually representing the […]

iOS/ObjC Interview Questions

General programming questions OOP basics: what is a class, interface, instance variable, methods, static (class) methods vs instance methods. Header vs implementation files What is a process, thread design patterns and principles blackbox vs whitebox testing differences? unit testing? integration testing? regression testing? what is continuous integration? difference between stack/heap General ObjC [expand title=”What do […]