App ID in iOS / App ID in iPhone

An App ID is a two-part string used to identify one or more apps from a single development team. The string consists of a Team ID and abundle ID search string, with a period (.) separating the two parts.The Team ID is supplied by Apple and is unique to a specific...

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Object copying in iOS / Object copying in iPhone / copy function call in iOS iPhone / what will happen when we call copy on object

Object copying Copying an object creates a new object with the same class and properties as the original object. You copy an object when you want your own version of the data that the object contains. If you receive an object from elsewhere in an application...

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what is Selector in iOS / what is Selector in iPhone

 A selector is the name used to select a method to execute for an object, or the unique identifier that replaces the name when the source code is compiled.  A selector by itself doesn’t do anything. It simply identifies a method. compiler makes sure that selectors are unique. What makes a selector useful is that (in conjunction...

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what is dispatch_once() in iOS / dispatch_once() in iOS

Executes a block object once and only once for the lifetime of an application. This function is useful for initialization of global data (singletons) in an application. Always call this function before using or testing any variables that are initialized by the block. If called simultaneously from multiple threads, this function waits synchronously...

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