Most projects need a singleton class or two. Even though it's mostly copy and paste, don't you wish they are easier to create?

Here's how:

@interface MyClass : NSObject

+ (MyClass*)sharedInstance;

@end

@implementation MyClass

+ (MyClass*)sharedInstance {
    DEFINE_SHARED_INSTANCE_USING_BLOCK(^{
        return [[self alloc] init];
    });
}

@end

The code above make use of the following macro:

#define DEFINE_SHARED_INSTANCE_USING_BLOCK(block) \
  static dispatch_once_t pred = 0; \
  __strong static id _sharedObject = nil; \
  dispatch_once(&pred, ^{ \
    _sharedObject = block(); \
  }); \
  return _sharedObject;

The macro is courtesy of: https://gist.github.com/1057420

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