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).
1.What are the differences between Cocoa and Cocoa Touch?
2.What is Xcode ?
3.What is the use of plist ?
4.What is .ipa in iOS ?
5.What is .xib in iOS ?
6.Your apps will scale automatically on iPhone 6, iPhone 6 Plus screens.
7.What are required delegates and data sources for Table View?
8.Some important notes about View in iPhone.