在块中返回 NSArray [重复]答案

【问题标题】：Return NSArray in block [duplicate]在块中返回 NSArray [重复]
【发布时间】：2014-06-25 16:02:08
【问题描述】：

如何返回完成块中正在填充的数组？它是一些 JSON 被解析成一个对象数组。

-(NSArray *)GetMapVehiclePoints
{
    NSString *methodURL = [NSString stringWithFormat:@"%@GetMapVehiclePoints", BASE_URL];
   __block NSArray *parsedVehicles = [[NSArray alloc]init];

    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
    [manager GET:methodURL parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {

        NSArray *vehicles = (NSArray *)responseObject;
        parsedVehicles = [self parseVehicles:vehicles];

    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        NSLog(@"Error: %@", error);
    }];

    return parsedVehicles;
}

每次我返回这个方法时，我都会得到一个空数组，因为完成块还没有运行。如何返回块内的数组？

【问题讨论】：

标签： ios objective-c afnetworking objective-c-blocks

【解决方案1】：

我要传递的是方法的完成块

- (void)GetMapVehiclePointsWithCompletion:(void (^)(NSArray *points))completion;

【讨论】：

【解决方案2】：

getMapVehiclePoints 不能/不应该返回一个数组。改用回调块...

typedef void(^CallbackBlock)(id value);

- (void)getMapVehiclePointsWithCallback:(CallbackBlock)callback {
    NSString *methodURL = [NSString stringWithFormat:@"%@GetMapVehiclePoints", BASE_URL];
    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
    [manager GET:methodURL parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
        if (callback) callback([self parseVehicles:(id)responseObject]);
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        NSLog(@"Error: %@", error);
        if (callback) callback(@[]);
    }];
}

[self getMapVehiclePointsWithCallback:^(NSArray *vehiclePoints) {
    NSLog(@"%@", vehiclePoints);
}];

【讨论】：