Example of Swift single case

Sometimes, we need a class as long as the initialization is enough, such as the audio player this instance, so we need to use a single case, familiar with C + + and OC know how to write

Class Csingleton/* Lazy */{public:    Static Csingleton * getinstance ()    {               if (m_pinstance = NULL)//Determine if the first call to 
   m_pinstance = new Csingleton;        return m_pinstance;    }        void Relaseinstance ()        {            Delete this;        } Private:        Csingleton ()//constructor is private        {        }        Csingleton (const csingleton& that)//copy constructor should also be private        {                }        ~csingleton ()        {            m_pinstance = NULL;        }        Static Csingleton *m_pinstance;         };

+ (singalclass*) shareinstance//  Singleton use the + sign, the following can be written as a macro call {//using GCD to create a singleton mode//first parameter predicate, This parameter is a predicate that checks whether the block of code represented by the second argument is called, and the second parameter is a block of code that will only be called once throughout the application. The code blocks in the Dispach_once function are only executed once and are thread-safe. Static dispatch_once_t once;dispatch_once (&once, ^{single=[singalclass alloc];}); return single;}

The Swfit is simpler:

Class Swiftysingleton {static let shared = Swiftysingleton ()//"Lazy instantiation" global variable is automatically placed in dispatch_once block [4] private init () {}}

Example of Swift single case