GKRuleSystem Class

Definition

Namespace:

GameplayKit

Assembly:

Xamarin.iOS.dll

Maintains a collection of GKRule objects, activating them as appropriate.

[Foundation.Register("GKRuleSystem", true)]
[ObjCRuntime.Introduced(ObjCRuntime.PlatformName.iOS, 9, 0, ObjCRuntime.PlatformArchitecture.All, null)]
[ObjCRuntime.Introduced(ObjCRuntime.PlatformName.MacOSX, 10, 11, ObjCRuntime.PlatformArchitecture.Arch64, null)]
public class GKRuleSystem : Foundation.NSObject

type GKRuleSystem = class
    inherit NSObject

Inheritance

Object

NSObject

GKRuleSystem

Attributes

RegisterAttribute IntroducedAttribute

Remarks

The GKRuleSystem class allows developers to build expert systems. Both classical and fuzzy-logic systems are supported.

At any time, a GKRule is either in the Agenda collection of rules to be evaluated or the Executed collection. The Reset() method moves all rules back to the Agenda collection.

The method Evaluate() evaluates the predicates of every rule in the Agenda, according to their Salience and, secondarily, the order in which they were added to the GKRuleSystem. Rules whose predicate evaluates to true have their action function executed and are placed in the Executed collection.

The following demonstrates the "FizzBuzz" challenge: If a number is evenly divisible by 3, output "fizz". If evenly divisible by 5, output "buzz". Otherwise, output the number itself. Note that this code properly sets the output to "buzzfizz" on an input of 15, since both the fizzRule and buzzRule evaluate to true.

var clearRule = GKRule.FromPredicate ((rules) => reset, rules => {
	output = "";
	reset = false;
});
clearRule.Salience = 1;

var fizzRule = GKRule.FromPredicate (mod (3), rules => {
	output += "fizz";
});
fizzRule.Salience = 2;
var buzzRule = GKRule.FromPredicate (mod (5), rules => { 
	output += "buzz";
});
buzzRule.Salience = 2;

var outputRule = GKRule.FromPredicate (rules => true, rules => {
	System.Console.WriteLine (output == "" ? input.ToString () : output);
	reset = true;
});
outputRule.Salience = 3;

var rs = new GKRuleSystem ();
rs.AddRules (new [] {
	clearRule,
	fizzRule,
	buzzRule,
	outputRule
});

for (input = 1; input < 16; input++) {
	rs.Evaluate ();
	rs.Reset ();
}

Constructors

GKRuleSystem()	Default constructor, initializes a new instance of this class.
GKRuleSystem(IntPtr)	A constructor used when creating managed representations of unmanaged objects; Called by the runtime.
GKRuleSystem(NSObjectFlag)	Constructor to call on derived classes to skip initialization and merely allocate the object.

Properties

Agenda	The collection of GKRule objects whose predicates have not yet evaluated to true.
Class	(Inherited from NSObject)
ClassHandle	The handle for this class.
DebugDescription	A developer-meaningful description of this object. (Inherited from NSObject)
Description	Description of the object, the Objective-C version of ToString. (Inherited from NSObject)
Executed	Rules in the system that have been evaluated as true and had their actions executed.
Facts	An arbitrary set of objects about which the GKRuleSystem maintains a truth grade in the range [0,1].
Handle	Handle (pointer) to the unmanaged object representation. (Inherited from NSObject)
IsDirectBinding	(Inherited from NSObject)
IsProxy	(Inherited from NSObject)
RetainCount	Returns the current Objective-C retain count for the object. (Inherited from NSObject)
Rules	All of the rules in the system, whether in Agenda or Executed.
Self	(Inherited from NSObject)
State	A mutable dictionary intended to hold the state information upon which the Rules operate.
Superclass	(Inherited from NSObject)
SuperHandle	Handle used to represent the methods in the base class for this NSObject. (Inherited from NSObject)
Zone	(Inherited from NSObject)

Methods

AddObserver(NSObject, NSString, NSKeyValueObservingOptions, IntPtr)	Registers an object for being observed externally (using NSString keyPath).   Observed changes are dispatched to the observer’s object ObserveValue(NSString, NSObject, NSDictionary, IntPtr) method. (Inherited from NSObject)
AddObserver(NSObject, String, NSKeyValueObservingOptions, IntPtr)	Registers an object for being observed externally (using string keyPath).   Observed changes are dispatched to the observer’s object ObserveValue(NSString, NSObject, NSDictionary, IntPtr) method. (Inherited from NSObject)
AddObserver(NSString, NSKeyValueObservingOptions, Action<NSObservedChange>)	Registers an object for being observed externally using an arbitrary method. (Inherited from NSObject)
AddObserver(String, NSKeyValueObservingOptions, Action<NSObservedChange>)	Registers an object for being observed externally using an arbitrary method. (Inherited from NSObject)
AddRule(GKRule)	Adds rule to the system, placing it in the Agenda.
AddRules(GKRule[])	Adds rules to the system, placing them in the Agenda.
AssertFact(NSObject, Single)	Adds the fact to the system's knowledge-base, increasing it's truth-value by grade.
AssertFact(NSObject)	Adds the fact to the system's knowledge-base, with a grade of 1.0.
AwakeFromNib()	Called after the object has been loaded from the nib file. Overriders must call base.AwakeFromNib(). (Inherited from NSObject)
BeginInvokeOnMainThread(Action)	(Inherited from NSObject)
BeginInvokeOnMainThread(Selector, NSObject)	Invokes asynchrously the specified code on the main UI thread. (Inherited from NSObject)
Bind(NSString, NSObject, String, NSDictionary)	(Inherited from NSObject)
Bind(String, NSObject, String, NSDictionary)	(Inherited from NSObject)
BindingInfo(String)	(Inherited from NSObject)
BindingOptionDescriptions(String)	(Inherited from NSObject)
BindingValueClass(String)	(Inherited from NSObject)
CommitEditing()	(Inherited from NSObject)
CommitEditing(NSObject, Selector, IntPtr)	(Inherited from NSObject)
ConformsToProtocol(IntPtr)	Invoked to determine if this object implements the specified protocol. (Inherited from NSObject)
Copy()	Performs a copy of the underlying Objective-C object. (Inherited from NSObject)
DangerousAutorelease()	(Inherited from NSObject)
DangerousRelease()	(Inherited from NSObject)
DangerousRetain()	(Inherited from NSObject)
DidChange(NSKeyValueChange, NSIndexSet, NSString)	Indicates a change occurred to the indexes for a to-many relationship. (Inherited from NSObject)
DidChange(NSString, NSKeyValueSetMutationKind, NSSet)	(Inherited from NSObject)
DidChangeValue(String)	Indicates that a change occurred on the specified key. (Inherited from NSObject)
Dispose()	Releases the resources used by the NSObject object. (Inherited from NSObject)
Dispose(Boolean)	Releases the resources used by the NSObject object. (Inherited from NSObject)
DoesNotRecognizeSelector(Selector)	Indicates that this object does not recognize the specified selector. (Inherited from NSObject)
Equals(NSObject)	(Inherited from NSObject)
Equals(Object)	(Inherited from NSObject)
Evaluate()	Evaluates the predicates in the Agenda and executes actions of those evaluating to true.
ExposedBindings()	(Inherited from NSObject)
GetBindingInfo(NSString)	(Inherited from NSObject)
GetBindingOptionDescriptions(NSString)	(Inherited from NSObject)
GetBindingValueClass(NSString)	(Inherited from NSObject)
GetDictionaryOfValuesFromKeys(NSString[])	Retrieves the values of the specified keys. (Inherited from NSObject)
GetGrade(NSObject)	Retrieves the truth grade for the fact.
GetHashCode()	Generates a hash code for the current instance. (Inherited from NSObject)
GetMaximumGrade(NSObject[])	Retrieves the maximum truth grade among the facts. (Fuzzy OR)
GetMethodForSelector(Selector)	(Inherited from NSObject)
GetMinimumGrade(NSObject[])	Retrieves the minimum truth grade among the facts. (Fuzzy AND)
GetNativeField(String)	Obsolete. (Inherited from NSObject)
GetNativeHash()	(Inherited from NSObject)
Init()	(Inherited from NSObject)
InitializeHandle(IntPtr, String)	(Inherited from NSObject)
InitializeHandle(IntPtr)	(Inherited from NSObject)
Invoke(Action, Double)	(Inherited from NSObject)
Invoke(Action, TimeSpan)	(Inherited from NSObject)
InvokeOnMainThread(Action)	(Inherited from NSObject)
InvokeOnMainThread(Selector, NSObject)	Invokes synchrously the specified code on the main UI thread. (Inherited from NSObject)
IsEqual(NSObject)	(Inherited from NSObject)
IsKindOfClass(Class)	(Inherited from NSObject)
IsMemberOfClass(Class)	(Inherited from NSObject)
MarkDirty()	Promotes a regular peer object (IsDirectBinding is true) into a toggleref object. (Inherited from NSObject)
MutableCopy()	Creates a mutable copy of the specified NSObject. (Inherited from NSObject)
ObjectDidEndEditing(NSObject)	(Inherited from NSObject)
ObserveValue(NSString, NSObject, NSDictionary, IntPtr)	Indicates that the value at the specified keyPath relative to this object has changed. (Inherited from NSObject)
PerformSelector(Selector, NSObject, Double, NSString[])	(Inherited from NSObject)
PerformSelector(Selector, NSObject, Double)	Invokes the selector on the current instance and if the obj is not null, it passes this as its single parameter. (Inherited from NSObject)
PerformSelector(Selector, NSObject, NSObject)	(Inherited from NSObject)
PerformSelector(Selector, NSObject)	(Inherited from NSObject)
PerformSelector(Selector, NSThread, NSObject, Boolean, NSString[])	(Inherited from NSObject)
PerformSelector(Selector, NSThread, NSObject, Boolean)	(Inherited from NSObject)
PerformSelector(Selector)	(Inherited from NSObject)
PrepareForInterfaceBuilder()	(Inherited from NSObject)
RemoveAllRules()	Removes all the GKRule objects in the GKRuleSystem.
RemoveObserver(NSObject, NSString, IntPtr)	Stops the specified observer from receiving further notifications of changed values for the specified keyPath and context. (Inherited from NSObject)
RemoveObserver(NSObject, NSString)	Stops the specified observer from receiving further notifications of changed values for the specified keyPath. (Inherited from NSObject)
RemoveObserver(NSObject, String, IntPtr)	Stops the specified observer from receiving further notifications of changed values for the specified keyPath and context. (Inherited from NSObject)
RemoveObserver(NSObject, String)	Stops the specified observer from receiving further notifications of changed values for the specified keyPath. (Inherited from NSObject)
Reset()	Moves all GKRule objects from the Executed collection to the Agenda.
RespondsToSelector(Selector)	Whether this object recognizes the specified selector. (Inherited from NSObject)
RetractFact(NSObject, Single)	Subtracts grade from the internal confidence in fact. If the internal confidence drops to 0.0, the fact is removed.
RetractFact(NSObject)	Removes the fact from the Facts collection.
SetNativeField(String, NSObject)	Obsolete. (Inherited from NSObject)
SetNilValueForKey(NSString)	Sets the value of the specified key to null. (Inherited from NSObject)
SetValueForKey(NSObject, NSString)	Sets the value of the property specified by the key to the specified value. (Inherited from NSObject)
SetValueForKeyPath(IntPtr, NSString)	A constructor used when creating managed representations of unmanaged objects; Called by the runtime. (Inherited from NSObject)
SetValueForKeyPath(NSObject, NSString)	Sets the value of a property that can be reached using a keypath. (Inherited from NSObject)
SetValueForUndefinedKey(NSObject, NSString)	Indicates an attempt to write a value to an undefined key. If not overridden, raises an NSUndefinedKeyException. (Inherited from NSObject)
SetValuesForKeysWithDictionary(NSDictionary)	Sets the values of this NSObject to those in the specified dictionary. (Inherited from NSObject)
ToString()	Returns a string representation of the value of the current instance. (Inherited from NSObject)
Unbind(NSString)	(Inherited from NSObject)
Unbind(String)	(Inherited from NSObject)
ValueForKey(NSString)	Returns the value of the property associated with the specified key. (Inherited from NSObject)
ValueForKeyPath(NSString)	Returns the value of a property that can be reached using a keypath. (Inherited from NSObject)
ValueForUndefinedKey(NSString)	Indicates an attempt to read a value of an undefined key. If not overridden, raises an NSUndefinedKeyException. (Inherited from NSObject)
WillChange(NSKeyValueChange, NSIndexSet, NSString)	Indicates that the values of the specified indices in the specified key are about to change. (Inherited from NSObject)
WillChange(NSString, NSKeyValueSetMutationKind, NSSet)	(Inherited from NSObject)
WillChangeValue(String)	Indicates that the value of the specified key is about to change. (Inherited from NSObject)

Extension Methods

GetDebugDescription(INSObjectProtocol)
GetAccessibilityCustomRotors(NSObject)	Gets the array of UIAccessibilityCustomRotor objects appropriate for this object.
SetAccessibilityCustomRotors(NSObject, UIAccessibilityCustomRotor[])	Sets the array of UIAccessibilityCustomRotor objects appropriate for this object.

See also

• Apple documentation for GKRuleSystem