DeluxeInjection 💉

Features

1. Auto-injection as first-class feature
2. Objective-C class properties support
3. Both value- and getter-/setter-injection supported
4. Inject both ivar-backed and @dynamic properties (over association)
5. Easily access ivar and original method implementation inside injected method

Table of contents

1. Concepts
2. Auto Injection
3. Lazies Injection
4. Settings Injection
5. Performance and Testing
6. Installation

Concepts

The main concept of DeluxeInjection library is explicit injection of marked properties. Properties can be marked with protocols, thats why integral (non-object) properties are not supported.

DeluxeInjection have minimal API and most interesting features are implemented like separated plugins. You can easily develop your own plugins, just looking at some existing: DIInject, DILazy, DIDefaults, DIAssociate.

Due DeluxeInjection architecture most plugins works by enumeration all properties of all classes. Thats not very optimal to use with several plugins, thats why DIImperative plugin was implemented, and all other plugins now support DIImperative plugin. It collects all injectable properties of all classes and provide you a block to apply all necessary injections in imperative format. This plugin is used to be default usage of DeluxeInjection.

Auto Injection

Here is basic example of injection value by class and protocol and getter injection:

@interface MyClass : NSObject

@property (nonatomic) Settings<DIInject> *settings;
@property (nonatomic) id<Analytics,DIInject> *analytics;
@property (nonatomic) NSMutableArray<UIVIew *><DIInject> *items;

@end

Create some instances to be injected:

Settings *settings = [UserDefaultsSetting new];
Analytics *analytics = [CountlyAnalytics new];

Inject instances and blocks to properties:

[DeluxeInjection imperative:^(DIImperative *lets) {

    // Inject value by class
    [[[lets inject] byPropertyClass:[Settings class]]
                    getterValue:settings];

    // Inject value by property protocol
    [[[lets inject] byPropertyProtocol:[Analytics class]]
                    getterValue:analytics];

    // Inject getter by property class
    [[[lets inject] byPropertyClass:[NSMutableArray class]]
                    getterBlock:DIImperativeGetterFromGetter(DIGetterMake(^id (id target, id *ivar) {
        if (*ivar == nil) {
            *ivar = [NSMutableArray array];
        }
        return *ivar;
    }))];
}];

You can inject value, getter and setter blocks. There are some functions to simplify getter (same for setters plus additional argument value) block definitions:

• DIGetterMake with block arguments: target and *ivar
• DIGetterIfIvarIsNil with block arguments: target
• DIGetterWithOriginalMake with block arguments: target, *ivar and original getter pointer

Lazies Injection

Do you really like this boilerplate?

@interface SomeClass : SomeSuperclass

@property (nonatomic) NSMutableArray *items;

@end

@implementation SomeClass

- (NSMutableArray *)items {
    if (_items == nil) {
        _items = [NSMutableArray array];
    }
    return items;
}

@end

Just one keyword will do this for you:

@interface SomeClass : SomeSuperclass

@property (nonatomic) NSMutableArray<DILazy> *items;

@end

Of course this will work for generic types:

@property (nonatomic) NSMutableArray<NSString *><DILazy> *items;
@property (nonatomic) NSMutableDictionary<NSString *, NSString *><DILazy> *items;

This all will be injected after calling injectLazy:

[DeluxeInjection imperative:^(DIImperative *lets) {
    ...
    [lets injectLazy];
    ...
}];

Settings Injection

Wanna achieve this behavior with less boilerplate code?

@interface SomeClass : SomeSuperclass

@property (nonatomic) NSString *username;

@end

@implementation SomeClass

- (NSString *)username {
    return [[NSUserDefaults standardUserDefaults] stringForKey:@"username"];
}

- (void)setUsername:(NSString *)username {
    return [[NSUserDefaults standardUserDefaults] setValue:username forKey:@"username"];
}

@end

Just use <DIDefaults> or <DIDefaultsSync> protocols on property declaration:

@interface SomeClass : SomeSuperclass

@property (nonatomic) NSString<DIDefaults> *username;

@end

Injections are made by calling injectDefaults:

[DeluxeInjection imperative:^(DIImperative *lets) {
    ...
    [lets injectDefaults];
    ...
}];

If something can not be stored directly to NSUserDefault it can be archived, just use DIDefaultsArchived or DIDefaultsArchivedSync protocols.

There are some extended versions of injectDefaults methods to provide key generator and use different NSUserDefaults instance:

• injectDefaultsWithKeyBlock:
• injectDefaultsWithDefaultsBlock:
• injectDefaultsWithKeyBlock:injectDefaultsWithKeyBlock:

Force injection

!!!Warning DIForceInject plugin can't be used in DIImperative manner and should be used in separate way.

You can force inject any property of any class:

@interface TestClass : SomeSuperclass

@property (nonatomic) Network *network;

@end

Even without any protocol specification using forceInject: method:

Network *network = [Network alloc] initWithSettings: ... ];
[DeluxeInjection forceInject:^id(Class targetClass,
                                 NSString *propertyName,
                 Class propertyClass,
                 NSSet<Protocol *> *protocols) {

    if ([target isKindOfClass:[TestClass class]] &&
        propertyClass == [Network class]) {

        return network;
    }
    return [DeluxeInjection doNotInject]; // Special value to skip injection
}];

Specified block will be called for all properties of all classes (exclude properties conforming any DI*** protocol) and you should determine which value to inject in this property, or not inject at all. You are also able to use method forceInjectBlock: to return DIGetter block instead of value to provide injected getter.

Performance and Testing

Single time enumeration of 100.000 properties in 40.000 classes with injecting 150 properties tooks 0.082 sec on my iPhone 6s in DEBUG configuration. Performance will not decrease in future versions, it is one of first-class feature of the library to be super-performant. You can find some performance test and other tests in Example project. I am planning to add as many tests as possible to detect all possible problems. May be you wanna help me with tests?

Installation

To run the example project, clone the repo, and run pod install from the Example directory first.

DeluxeInjection is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'DeluxeInjection'

Author

Anton Bukov [email protected] https://twitter.com/k06a

License

DeluxeInjection is available under the MIT license. See the LICENSE file for more info.

Contribution

– Wanna really help to project?
– Help me to add more test and divide them by plugins.

– Found any bugs?
– Feel free to open issue or talk to me directly @k06a!

Contribution workflow:
1. Fork repository
2. Create new branch from master
3. Commit to your newly created branch
4. Open Pull Request and we will talk :)