A Cocoa Touch Framework with MulticastDelegator Class to Establish a 1-to-many Relationship of Delegator to Delegate. Compatible with Swift (Objects only) and Objective-C.
The MulticastDelegator class can be used to establish a pattern of delegation that is a variation on the typical Cocoa delegate design pattern. Specifically, instead of a one-to-one relationship from delegator to delegate, a one-to-many relationship is used.
- The MulticastDelegator has one or more delegates. They are maintained via a set of weak references (implemented with an NSHashTable of weak objects).
- The delegates are not required to remove themselves from the MulticastDelegator's set as the MulticastDelegator holds only weak references to its delegates.
// MARK: - Define a protocol
// Protocol must inherit from AnyObject to maintain compatibility with Objective-C
@objc protocol MyProtocol: AnyObject {
@objc func requiredMethodWithBoolean(_ boolean: Bool)
@objc optional func optionalMethod()
}
// MARK: - Define objects that conform to the protocol
class MyFirstProtocolObject: MyProtocol {
func requiredMethodWithBoolean(_ boolean: Bool) {
}
}
class MySecondProtocolObject: MyProtocol {
func requiredMethodWithBoolean(_ boolean: Bool) {
}
func optionalMethod() {
}
}
// MARK: - Usage
func usageExample() {
let delegator = MulticastDelegator<MyProtocol>()
let firstDelegate = MyFirstProtocolObject()
let secondDelegate = MySecondProtocolObject()
delegator.addDelegate(firstDelegate)
delegator.addDelegate(secondDelegate)
delegator.invokeDelegates { (delegate: MyProtocol) in
delegate.requiredMethodWithBoolean(true)
}
delegator.invokeDelegates { (delegate: MyProtocol) in
delegate.optionalMethod?()
}
}#pragma mark - Define a Protocol
@protocol MyProtocol <NSObject>
- (void)requiredMethodWithBoolean:(BOOL)boolean;
@optional
- (void)optionalMethod;
@end
#pragma mark - Define objects that conform to the protocol
@interface MyFirstProtocolObject: NSObject <MyProtocol>
@end
@implementation MyFirstProtocolObject
- (void)requiredMethodWithBoolean:(BOOL)boolean
{
}
- (void)optionalMethod
{
}
@end
@interface MySecondProtocolObject: NSObject <MyProtocol>
@end
@implementation MySecondProtocolObject
- (void)requiredMethodWithBoolean:(BOOL)boolean
{
}
@end
#pragma mark - Usage
void usageExample()
{
MulticastDelegator<id<MyProtocol>> *delegator = [MulticastDelegator new];
id<MyProtocol> firstDelegate = [MyFirstProtocolObject new];
id<MyProtocol> secondDelegate = [MySecondProtocolObject new];
[delegator addDelegate:firstDelegate];
[delegator addDelegate:secondDelegate];
[delegator invokeDelegates:^(id<MyProtocol> delegate) {
[delegate requiredMethodWithBoolean:YES];
}];
[delegator invokeDelegates:^(id<MyProtocol> delegate) {
if ([delegate respondsToSelector:@selector(optionalMethod)])
{
[delegate optionalMethod];
}
}];
}