objective-c - objective-c 在while循环中处理其他事件

Question

有没有办法强制您的应用程序处理其他事件？我有一个循环应该等待 10 秒以获得 json 响应。问题似乎是在 didReceiveData 事件可以运行之前循环处理。

JsonArray 是一个 NSArray 属性。

这是我在 Session.m 中的代码:

-(BOOL)logIn
{
    JsonArray = nil;
    if (([Password class] == [NSNull class]) || ([Password length] == 0))
        return NO;

    if (([Username class] == [NSNull class]) || ([Username length] == 0))
        return NO;

    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:URL_ALL_PROPERTIES]
                                             cachePolicy:NSURLRequestUseProtocolCachePolicy
                                         timeoutInterval:10.0];

    NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
    [connection start];

    if (!connection)
    {
        return NO;
    }

    int time = CFAbsoluteTimeGetCurrent();

    while (!JsonArray)
    {
        if (CFAbsoluteTimeGetCurrent() - time == 10)
        {
            NSLog(@"breaking loop");
            break;
        }
        // process events here
    }

    if (!JsonArray) return NO;

    NSLog(@"JsonArray not nil");
    return YES;
}

didReceiveData 处理程序:

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
    NSLog(@"Data received");
    NSError *e = nil;
    JsonArray = nil;

    JsonArray = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:&e];
    if (!JsonArray)
    {
        JsonArray = nil;
        Connected = NO;
        return;
    }
    Connected = YES;
}

Answer 1

拥抱你正在尝试做的事情的异步性质。从 login 中删除返回方法并添加一个完成 block 。将完成 block 存储在属性中(副本)并从 connectionDidFinishLoading: 调用它.

typedef void (^MYCompletionHandler)(BOOL success);

@property (nonatomic, copy) void (^MYCompletionHandler)(bool *) completion;

- (void)loginUserWithCompletion:(MYCompletionHandler)completion {

    self.completion = completion;

    // start your login processing here
}

// when the login response is received
self. completion(##DID_IT_WORK##);

您当前的代码不起作用，因为在您的硬循环运行时主运行循环没有运行，因此委托(delegate)方法排队等待处理。不要尝试使用运行循环来解决它，正确处理异步性质。