MessageThrottle is a lightweight, simple library for controlling frequency of forwarding Objective-C messages. You can choose to control existing methods per instance or per class. It's an implementation of function throttle/debounce developed with Objective-C runtime. For a visual explaination of the differences between throttling and debouncing, see this demo.

• Objective-C Message Throttle and Debounce
• Associated Object and Dealloc
• MessageThrottle Performance Benchmark and Optimization
• MessageThrottle Safety

• Easy to use.
• Keep your code clear
• Reserve the whole arguments.
• Support instance, class and meta class.
• Support 3 modes: Throttle(Firstly), Throttle(Last) and Debounce.
• Centralized management of rules.
• Self-managed rules.
• Let method MUST invoke at the specified conditions.
• Persistent rules.

To run the example project, clone the repo and run MTDemo target.

The following example shows how to restrict the frequency of forwarding - [ViewController foo:] message to 100 times per second.

Stub *s = [Stub new];
MTRule *rule = [s limitSelector:@selector(foo:) oncePerDuration:0.01]; // returns MTRule instance

For more control of rule, you can use mt_limitSelector:oncePerDuration:usingMode:onMessageQueue:alwaysInvokeBlock:.

You can also start with a creation of MTRule:

Stub *s = [Stub new];
// You can also assign `Stub.class` or `mt_metaClass(Stub.class)` to `target` argument.
MTRule *rule = [[MTRule alloc] initWithTarget:s selector:@selector(foo:) durationThreshold:0.01];
rule.mode = MTModePerformLast; // Or `MTModePerformFirstly`, ect
[rule apply];

You can let method MUST invoke at the specified conditions using alwaysInvokeBlock. The example code above will invoke message immediately if its 1st parameter equals "1970". BTW, alwaysInvokeBlock can has no parameter, or has one more MTRule before message's parameter list.

You should call discard method When you don't need limit foo: method.

[rule discard];

NOTE: MTRule is self-managed. If the target of rule is a object instance, MTRule will discard itself automatically when the target is deallocated.

Some rules may have large durationThreshold. You can set property persistent to YES, and save them on disk by calling savePersistentRules method. These persistent rules will be applied after MTEngine class is loaded. savePersistentRules will be called automatically when receive terminate notification.

rule.persistent = YES;
[MTEngine.defaultEngine savePersistentRules];

MTRule represents the rule of a message throttle, which contains strategy and frequency of sending messages.

You can assign an instance or (meta)class to target property. When you assign an instance to target, MessageThrottle will only restrict messages send to this instance. If you want to restrict a class method, just using mt_metaClass() to get it's meta class, and assign the meta class to target. Rules with instance target won't conflict with each other, and have a higher priority than rules with class target.

NOTE: A message can only have one rule per class hierarchy. For example, If there is one rule of message - [Stub foo:], you can't add another rule of message - [SuperStub foo:] anymore. PS: Assume that Stub is a subclass of SuperStub.

MTRule also define the mode of performing selector. There are three modes defined in MTMode: MTModePerformFirstly, MTModePerformLast and MTModePerformDebounce. This demo shows the difference between throttle and debounce.

The default mode is MTModePerformDebounce. MTModePerformDebounce will restart timer when another message arrives during durationThreshold. So there must be a delay of durationThreshold at least.

MTModePerformDebounce:
start                                        end
|           durationThreshold(old)             |
@----------------------@---------------------->>
|                      |                 
ignore                 will perform at end of new duration
                       |--------------------------------------------->>
                       |           durationThreshold(new)             |
                       start                                        end

MTModePerformFirstly will performs the first message and ignore all following messages during durationThreshold.

MTModePerformFirstly:
start                                                                end
|                           durationThreshold                          |
@-------------------------@----------@---------------@---------------->>
|                         |          |               |          
perform immediately       ignore     ignore          ignore     

MTModePerformLast performs the last message at end time. Please note that does not perform message immediately, the delay could be durationThreshold at most.

MTModePerformLast:
start                                                                end
|                           durationThreshold                          |
@-------------------------@----------@---------------@---------------->>
|                         |          |               |          
ignore                    ignore     ignore          will perform at end

When using MTModePerformLast or MTModePerformDebounce, you can designate a dispatch queue which messages perform on. The messageQueue is main queue by default. MTModePerformLast and MTModePerformDebounce modes will also use the last arguments to perform messages.

MTEngine is a singleton class. It manages all rules of message throttles. You can use applyRule: method to apply a rule or update an old rule that already exists. Using it's discardRule: method to discardRule a rule. There is also a readonly property allRules for obtaining all rules in current application.

CocoaPods is a dependency manager for Cocoa projects. You can install it with the following command:

$ gem install cocoapods

To integrate MessageThrottle into your Xcode project using CocoaPods, specify it in your Podfile:

source 'https://github.com/CocoaPods/Specs.git'
platform :ios, '11.0'
use_frameworks!
target 'MyApp' do
	pod 'MessageThrottle'
end

You need replace "MyApp" with your project's name.

Then, run the following command:

$ pod install

Carthage is a decentralized dependency manager that builds your dependencies and provides you with binary frameworks.

You can install Carthage with Homebrew using the following command:

$ brew update
$ brew install carthage

To integrate MessageThrottle into your Xcode project using Carthage, specify it in your Cartfile:

github "yulingtianxia/MessageThrottle"

Run carthage update to build the framework and drag the built MessageThrottleKit.framework into your Xcode project.

Just drag the "MessageThrottle" document folder into your project.

• If you need help or you'd like to ask a general question, open an issue.
• If you found a bug, open an issue.
• If you have a feature request, open an issue.
• If you want to contribute, submit a pull request.

yulingtianxia, [email protected]

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