swiftly单例

swiftly的单例比OC的更加简单！

class MySingletonClass {  
  static let sharedInstance = MySingletonClass()        
   private init() {  
    }  
  }

Oc中的单例：

  @implementation MySingletonClass  
+(id)sharedInstance {  
    static MySingletonClass *sharedInstance = nil;  
    static dispatch_once_t onceToken;  
    dispatch_once(&onceToken, ^{  
        sharedInstance = [[self alloc] init];  
    });  
    return sharedInstance;  
}