90 lines
2.8 KiB
Objective-C
90 lines
2.8 KiB
Objective-C
//
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// NSObject+A2DynamicDelegate.m
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// BlocksKit
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//
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#import "NSObject+A2DynamicDelegate.h"
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@import ObjectiveC.runtime;
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#import "A2DynamicDelegate.h"
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extern Protocol *a2_dataSourceProtocol(Class cls);
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extern Protocol *a2_delegateProtocol(Class cls);
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static Class a2_dynamicDelegateClass(Class cls, NSString *suffix)
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{
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while (cls) {
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NSString *className = [NSString stringWithFormat:@"A2Dynamic%@%@", NSStringFromClass(cls), suffix];
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Class ddClass = NSClassFromString(className);
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if (ddClass) return ddClass;
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cls = class_getSuperclass(cls);
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}
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return [A2DynamicDelegate class];
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}
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static dispatch_queue_t a2_backgroundQueue(void)
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{
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static dispatch_once_t onceToken;
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static dispatch_queue_t backgroundQueue = nil;
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dispatch_once(&onceToken, ^{
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backgroundQueue = dispatch_queue_create("BlocksKit.DynamicDelegate.Queue", DISPATCH_QUEUE_SERIAL);
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});
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return backgroundQueue;
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}
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@implementation NSObject (A2DynamicDelegate)
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- (id)bk_dynamicDataSource
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{
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Protocol *protocol = a2_dataSourceProtocol([self class]);
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Class class = a2_dynamicDelegateClass([self class], @"DataSource");
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return [self bk_dynamicDelegateWithClass:class forProtocol:protocol];
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}
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- (id)bk_dynamicDelegate
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{
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Protocol *protocol = a2_delegateProtocol([self class]);
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Class class = a2_dynamicDelegateClass([self class], @"Delegate");
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return [self bk_dynamicDelegateWithClass:class forProtocol:protocol];
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}
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- (id)bk_dynamicDelegateForProtocol:(Protocol *)protocol
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{
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Class class = [A2DynamicDelegate class];
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NSString *protocolName = NSStringFromProtocol(protocol);
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if ([protocolName hasSuffix:@"Delegate"]) {
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class = a2_dynamicDelegateClass([self class], @"Delegate");
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} else if ([protocolName hasSuffix:@"DataSource"]) {
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class = a2_dynamicDelegateClass([self class], @"DataSource");
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}
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return [self bk_dynamicDelegateWithClass:class forProtocol:protocol];
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}
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- (id)bk_dynamicDelegateWithClass:(Class)cls forProtocol:(Protocol *)protocol
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{
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/**
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* Storing the dynamic delegate as an associated object of the delegating
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* object not only allows us to later retrieve the delegate, but it also
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* creates a strong relationship to the delegate. Since delegates are weak
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* references on the part of the delegating object, a dynamic delegate
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* would be deallocated immediately after its declaring scope ends.
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* Therefore, this strong relationship is required to ensure that the
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* delegate's lifetime is at least as long as that of the delegating object.
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**/
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__block A2DynamicDelegate *dynamicDelegate;
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dispatch_sync(a2_backgroundQueue(), ^{
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dynamicDelegate = objc_getAssociatedObject(self, (__bridge const void *)protocol);
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if (!dynamicDelegate)
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{
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dynamicDelegate = [[cls alloc] initWithProtocol:protocol];
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objc_setAssociatedObject(self, (__bridge const void *)protocol, dynamicDelegate, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
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}
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});
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return dynamicDelegate;
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}
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@end
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