Declaring a property atomic makes compiler generate additional code that prevents concurrent access to the property. This additional code locks a semaphore, then gets or sets the property, and then unlock the semaphore. Compared to setting or getting a primitive value or a pointer, locking and unlocking a semaphore is expensive (although it is usually negligible if you consider the overall flow of your app).
A design pattern is a template for a design that solves a general, recurring problem in a particular context. It is a tool of abstraction that is useful in fields like architecture and engineering as well as software development.
Model-View-Controller -pattern (MVC) used throughout the Cocoa Touch.
MVC is used to separate the application data from the way it is displayed on screen. Model refers to the application data model, such as a database of names, dates of birth and so on.
Serving as a table's delegate means you provide answers to requests about the layout of the table and about actions the user performs on the tableview. Layout methods include the tableview asking about the height of rows, headers, and footers, what the buttons should look like, etc. Action methods include the user selecting a row and beginning and ending the editing of a row.
Apple launches iPhone 6 (4.7 inches,1334X750 pixels) and iPhone 6 Plus (5.5 inches,1920X1080 pixels).It means that developers will have to redo extra work to make their apps compatible on larger zscreens,right?.Now, there are 1.3 million apps on iOS, there's a good chance that developers are likely to look to update their apps to take advantage of extra resolution.
I am Jitendra Gochhayat, an iOS developer,blogger, from Odisha,India. I write about Objective C tutorials,iOS interview Questions And Answers,swift tutorials and cocos2d-x sample codes to help the developers.