Question

我正在从同步调用转移到异步调用，并想知道实现条件异步请求的好方法是什么？

例如，我有以下方法：

-(void)getSomeData:(NSInteger)data
{
    [Set data which will be used in the layout]

    if (data == 1)
    {
        AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
        [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {

            [Set data which will be used in the layout]
            [Do Some layout calls]
        }
    }

    [Do Some layout calls]
}

在获取数据异步时，以及在不满足条件时，需要执行[Do some layout calls]。

我有很多像这样的方法，似乎它会产生很多“重复”的代码，或者需要大量的方法提取。

Answer 1

您可以使用块来避免代码重复。

- (void)getSomeData:(NSInteger)data
{
    void(^setData)(void) = ^(void) {
        [Set data which will be used in the layout]
    };

    void(^doLayoutJob)(void) = ^(void) {
        [Do Some layout calls]
    };


    setData();
    if (data == 1)
    {
        AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
        [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {

            setData();                 
            doLayoutJob();
        }
    }

    doLayoutJob();
}

Answer 2

在完成块中获取数据，然后调用将设置数据并执行一些布局的函数。您可以根据您的条件调用get data completion block。

- (void)setUp
{
    NSData *data = nil;
    [self setUpData:data];
    if (data)
    {
        [self getDataFromUrlString:@"URL" dataCompletion:^(id data) {
            [self setUpData:data];
        }];
    }
}

- (void)setUpData:(id)data
{
    [Set data which will be used in the layout];
    [Do Some layout calls]
}

- (void)getDataFromUrlString:(NSString *)urlString dataCompletion:(void(^)(id data))dataCompletion {
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^(void) {
        NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:urlString]];
        dispatch_sync(dispatch_get_main_queue(), ^(void) {
            dataCompletion(data);
        });
    });
}

带有目标c的条件异步调用

2 个答案: