Multiton 2.1.1

Multiton is a better alternative to singleton. It's more flexible and require less code lines to implement.

Features:

• Make shared instance of class just by including ABMultitonProtocol to class interface. No implementation needed!
• Remove shared instance of class when you don't need it anymore (unit-tests!). No more immortal instances!
• Specify is shared instance should be removed on memory warning.
• Create shared instance with custom init method with arguments.
• Set custom instance that will return as shared.

Warning

This is not implementation of classic multiton. This implementation uses instance class name as key to access instance.

Installation

Add to Podfile

pod 'ABMultiton'

Using

1. Shared instance

Class should conforms to ABMultitonProtocol

#import "ABMultitonProtocol.h"
...
@interface MyClass : ParentClass <ABMultitonProtocol>
...
@end

And that's all! ABMultiton will add shared method implementation in runtime. And you can access shared instance just like this:

[MyClass.shared myMethod];

2. Shared instance with custom initilization

ABMultiton implements shared method in this way

return [[MyClass alloc] init];

And if you need to use some custom init method you should implement shared method by yourself in this way:

#import "ABMultiton.h"
...
+ (instancetype)shared
{
    return [ABMultiton sharedInstanceOfClass:self.class withInitBlock:^id
    {
        MyClass *instance = [[MyClass alloc] initWithArgument:value];
        instance.someProperty = propertyValue;
        return instance;
    }];
}

3. Remove shared instance

It's very useful in unit tests. So, if you don't need shared instance you can remove it by this call:

[MyClass removeShared];

This method is also injected by ABMultiton in runtime. Here is method implementation:

[ABMultiton removeInstanceOfClass:MyClass.class];

4. Remove shared instance on memory warning

Sometimes you don't need shared instance for all app life cycle. And you may want to release some shared instances on low memory. It's pretty easy. Just implement optional method isRemovableInstance of ABMultitonProtocol

@implementation MyClass
...
- (BOOL)isRemovableInstance
{
    return YES;
}

And this instance will be released on memory warning. Or you can release all such instances manually by this call:

[ABMultiton purgeRemovableInstances];

5. Check is shared instance exists

BOOL isExists = [ABMultiton containsInstanceOfClass:[MyClass class]];

6. Thread safety

Using ABMultiton is thread safe.

7. Important warning

Please, don't create shared instance for class if you can. "Singleton mania" is a well known anti-pattern.

Subspec

ABMultiton contain subspec SetInstance. It's allow to replace or add instance for class that will return on shared method call. It can be very useful with unit-tests.

Installation

Replace pod 'ABMultiton' with pod 'ABMultiton/SetInstance'

Using

[ABMultiton setInstance:customInstance forClass:MyClass.class];

History

Releases

Updates

Stay tuned with ABMultiton updates at @okolodev