Objective-CブロックとC ++ラムダ

int multiplier = 7; int (^myBlock)(int) = ^(int num) { return num * multiplier;}; NSLog(@”%d”, myBlock(4)); //  28 

• ^-この記号は、変数がブロックであることをコンパイラーに伝えます
• int-ブロックはint型のパラメーターを1つ受け入れ、int型のパラメーターを返します
• 乗数-コンテキストから取得される変数（これについては、「コンテキストのキャプチャ」セクションを参照してください）

 //   @implementation NSArray (Blocks) //   ,     - (NSArray*)subarrayWithPredicate:(BOOL(^)(id object, NSUInteger idx, BOOL *stop))predicte { NSMutableArray *resultArray = [NSMutableArray array]; BOOL shouldStop = NO; for (id object in self) { if (predicte(object, [self indexOfObjectIdenticalTo:object], &shouldStop)) { [resultArray addObject:object]; } if (shouldStop) { break; } } return [[resultArray copy] autorelease]; } @end // -    NSArray *numbers = @[@(5), @(3), @(8), @(9), @(2)]; NSUInteger divisor = 3; NSArray *divisibleArray = [numbers subarrayWithPredicate:^BOOL(id object, NSUInteger idx, BOOL *stop) { BOOL shouldAdd = NO; //     3 NSAssert([object isKindOfClass:[NSNumber class]], @"object != number"); //  ,   divisor     if ([(NSNumber *)object intValue] % divisor == 0) { shouldAdd = YES; } return shouldAdd; }]; NSLog(@"%@", divisibleArray); //  3, 9 

 typedef int (^MyBlockType)(int number, id object); 

 int multiplier = 7; auto lambda = [&multiplier](int num) throw() -> int { return multiplier * num; }; lambda(4); //  28 

• [] -ラムダ宣言の開始、内部-コンテキストキャプチャ
• &multiplier -キャプチャされた変数（ &参照によりキャプチャされた手段）
• int入力パラメーター
• mutable値でキャプチャされた変数を変更できるキーワード
• throw() -ラムダが外部に例外をスローしないことを意味します

 template<class InputCollection, class UnaryPredicate> void subset(InputCollection& inputCollection, InputCollection& outputCollection, UnaryPredicate predicate) { typename InputCollection::iterator iterator = inputCollection.begin(); for (;iterator != inputCollection.end(); ++iterator) { if (predicate(*iterator)) { outputCollection.push_back(*iterator); } } return; } int main(int argc, const char * argv[]) { int divisor = 3; std::vector<int> inputVector = {5, 3, 8, 9, 2}; std::vector<int> outputVector; subset(inputVector, outputVector, [divisor](int number){return number % divisor == 0;}); //     std::for_each( outputVector.begin(), outputVector.end(), [](const int& number){std::cout << number << std::endl;} ); } 

 __block int first = 7; void (^myBlock2)(int) = ^(int second) { first += second;}; myBlock2(4); NSLog(@"%d", first); //  11 

 NSMutableArray *array = [NSMutableArray array]; void (^myBlock3)() = ^() { [array addObject:@"someString"];}; myBlock3(); //  someString  array 

 typedef void (^PKHTTPRequestCompletionSuccessBlock)(NSString *responseString); typedef void (^PKHTTPRequestCompletionFailBlock)(NSError* error); @protocol PKRequest <NSObject> - (void)startRequest; @end @interface PKHTTPRequest : NSObject <PKRequest> // designated initializer - (id)initWithURL:(NSURL *)url successBlock:(PKHTTPRequestCompletionSuccessBlock)success failBlock:(PKHTTPRequestCompletionFailBlock)fail; @end 

 @interface PKHTTPRequest () <NSURLConnectionDelegate> @property (nonatomic, copy) PKHTTPRequestCompletionSuccessBlock succesBlock; @property (nonatomic, copy) PKHTTPRequestCompletionFailBlock failBlock; @property (nonatomic, retain) NSURL *url; @property (nonatomic, retain) NSURLConnection *connection; @property (nonatomic, retain) NSMutableData *data; @end @implementation PKHTTPRequest #pragma mark - initialization / deallocation // designated initializer - (id)initWithURL:(NSURL *)url successBlock:(PKHTTPRequestCompletionSuccessBlock)success failBlock:(PKHTTPRequestCompletionFailBlock)fail { self = [super init]; if (self != nil) { self.succesBlock = success; self.failBlock = fail; self.url = url; NSURLRequest *request = [NSURLRequest requestWithURL:self.url]; self.connection = [[[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:NO] autorelease]; } return self; } - (id)init { NSAssert(NO, @"Use desiganted initializer"); return nil; } - (void)dealloc { self.succesBlock = nil; self.failBlock = nil; self.url = nil; self.connection = nil; self.data = nil; [super dealloc]; } #pragma mark - public methods - (void)startRequest { self.data = [NSMutableData data]; [self.connection start]; } #pragma mark - NSURLConnectionDelegate implementation - (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { [self.data appendData:data]; } - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error { self.failBlock(error); self.data = nil; } - (void)connectionDidFinishLoading:(NSURLConnection *)connection { self.succesBlock([NSString stringWithUTF8String:self.data.bytes]); self.data = nil; } @end 

 typedef void (^PKGetUserNameRequestCompletionSuccessBlock)(NSString *userName); typedef void (^PKGetUserNameRequestCompletionFailBlock)(NSError* error); @interface PKGetUserNameRequest : NSObject <PKRequest> - (id)initWithUserID:(NSString *)userID successBlock:(PKGetUserNameRequestCompletionSuccessBlock)success failBlock:(PKGetUserNameRequestCompletionFailBlock)fail; @end 

 NSString *kApiHost = @"http://someApiHost.com"; NSString *kUserNameApiKey = @"username"; @interface PKGetUserNameRequest () @property (nonatomic, retain) PKHTTPRequest *httpRequest; - (NSString *)parseResponse:(NSString *)response; @end @implementation PKGetUserNameRequest #pragma mark - initialization / deallocation - (id)initWithUserID:(NSString *)userID successBlock:(PKGetUserNameRequestCompletionSuccessBlock)success failBlock:(PKGetUserNameRequestCompletionFailBlock)fail { self = [super init]; if (self != nil) { NSString *requestString = [kApiHost stringByAppendingFormat:@"?%@=%@", kUserNameApiKey, userID]; self.httpRequest = [[[PKHTTPRequest alloc] initWithURL:[NSURL URLWithString:requestString] successBlock:^(NSString *responseString) { //   -   self NSString *userName = [self parseResponse:responseString]; success(userName); } failBlock:^(NSError *error) { fail(error); } ] autorelease]; } return self; } - (id)init { NSAssert(NO, @"Use desiganted initializer"); return nil; } - (void)dealloc { self.httpRequest = nil; [super dealloc]; } #pragma mark - public methods - (void)startRequest { [self.httpRequest startRequest]; } #pragma mark - private methods - (NSString *)parseResponse:(NSString *)response { /* ...... */ return userName; } @end 

 //    __block PKGetUserNameRequest *selfRequest = self; self.httpRequest = [[[PKHTTPRequest alloc] initWithURL:[NSURL URLWithString:requestString] successBlock:^(NSString *responseString) { NSString *userName = [selfRequest parseResponse:responseString]; success(userName); } failBlock:^(NSError *error) { fail(error); } ] autorelease]; 

 void addBlockToArray(NSMutableArray* array) { NSString *string = @"example string"; [array addObject:^{ printf("%@\n", string); }]; } void example() { NSMutableArray *array = [NSMutableArray array]; addBlockToArray(array); void (^block)() = [array objectAtIndex:0]; block(); } 

 //  №1 auto lamb = []() {return 5;}; auto func_lamb_ptr = new std::function<int()>(lamb); //  №2: auto lamb = []() {return 5;}; auto* p = new decltype(lamb)(lamb); //  №3: template <typename T> T* heap_alloc(T const& value) { return new T(value); } auto* p = heap_alloc([]() {return 5;}); //  №4: std::vector<decltype(lamb)> v; v.push_back(lamb);