利用 GCD 信号量、NSOperation管理请求

需求：若干个request依次执行，若其中一个失败，则取消剩余未执行的request

1.自定义operation

// .h实现如下
@protocol CustomOperationDelegate <NSObject>

- (void)cancelAllRequest:(NSInteger)index params:(NSDictionary *)dict isSuccess:(BOOL)isSuccess;

@end
@interface CustomOperation : NSOperation

@property (nonatomic, copy) NSString *params;
@property (nonatomic, strong) dispatch_semaphore_t sema;
@property (nonatomic, assign) NSInteger index;
@property (nonatomic, weak) id<CustomOperationDelegate> delegate;

@end 

#import <AFNetworking.h>

@implementation CustomOperation

- (void)main {
    if (!self.isCancelled) {
        NSString * url = [NSString stringWithFormat:@"%@%@",@"http://220.174.234.36:8090/GasAPITest/",@"house/customerNoHouse"];
        NSMutableDictionary * paraDic = [NSMutableDictionary dictionary];
        [paraDic setObject:self.params forKey:@"customerNo"];
        
        __block BOOL isSuccessed = YES;
        __block NSDictionary *dict = [NSDictionary dictionary];
        
        [[AFHTTPSessionManager manager] POST:url parameters:paraDic
                                    progress:^(NSProgress * _Nonnull uploadProgress) {
                                        
                                    } success:^(NSURLSessionDataTask * _Nonnull task, id  _Nullable responseObject) {
                                        if ([responseObject[@"result"] isEqualToString:@"success"]) {
                                            isSuccessed = YES;
                                            dict = responseObject;
                                        } else {
                                            isSuccessed = NO;
                                        }
                                        dispatch_semaphore_signal(self.sema);
                                        
                                    } failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
                                        isSuccessed = NO;
                                        dispatch_semaphore_signal(self.sema);
                                        
                                    }];
        
        dispatch_semaphore_wait(self.sema, DISPATCH_TIME_FOREVER);
        
        [self.delegate cancelAllRequest:self.index params:dict isSuccess:isSuccessed];

    }
}
@end 

2. 应用如下

#import "ViewController.h"
#import "CustomOperation.h"

@interface ViewController () <CustomOperationDelegate>

@property (nonatomic, strong) NSOperationQueue *queue;
@property (nonatomic, strong) NSMutableArray *array;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
   
    self.array = [NSMutableArray array];
    
    self.queue = [[NSOperationQueue alloc] init];
    self.queue.maxConcurrentOperationCount = 1;
    dispatch_semaphore_t semaphore =dispatch_semaphore_create(0);
    
    CustomOperation *operationToAdd;
    NSArray *gasNumberArr =@[@"00047449",@"00047449",@"3",@"00047449",@"00047449"];
    for (NSInteger i=0; i<gasNumberArr.count; i++) {
        operationToAdd = [[CustomOperation alloc] init];
        operationToAdd.params = gasNumberArr[i];
        operationToAdd.index = i;
        operationToAdd.sema = semaphore;
        operationToAdd.delegate = self;
        NSOperation *lastOperation = self.queue.operations.lastObject;
        if (lastOperation) {
            [operationToAdd addDependency:lastOperation];
        }
        [self.array addObject:operationToAdd];
        [self.queue addOperation:operationToAdd];
    }
}

- (void)cancelAllRequest:(NSInteger)index params:(NSDictionary *)dict isSuccess:(BOOL)isSuccess {
    NSLog(@"---index--%@---dic---%@----#%@", @(index), dict, @(isSuccess));
    
    if (!isSuccess) {
        if (index+1 < self.array.count) {
            for (NSInteger i=index + 1; i<self.array.count; i++) {
                CustomOperation *oper = self.array[i];
                [oper cancel];
            }
        }
    }
}

@end

3.结果如下：