ios - NSTimer，当我回到 ViewController 时不会启动

Question

我有一个 NSTimer，它每 25 秒发出一个 HTTP 请求。这工作正常，但是当我转到另一个 ViewController 然后返回时。它可能不起作用。我做错了什么？

-(void)viewDidAppear:(BOOL)animated {

    timer = [NSTimer timerWithTimeInterval:26.0 target:self selector:@selector(sendRequestToGetData:) userInfo:nil repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSDefaultRunLoopMode];

}

NSTimer

-(void)sendRequestToGetData:(NSTimer *)timer
{


NSDictionary *headers = @{},
*parameters = @{};

UNIHTTPJsonResponse *response = [[UNIRest get:
                                  ^(UNISimpleRequest* request) {
                                      [request setUrl:
                                       @"http://localhost/getfixture.php/fixtures"
                                       ];

                                      [request setHeaders:headers];
                                      [request setParameters:parameters];
                                  }] asJson];

NSData* rawBody = [response rawBody];
jsonResult = [NSJSONSerialization JSONObjectWithData: rawBody
                                             options: NSJSONReadingMutableContainers
                                               error: nil];

}

Answer 1

试试这个:

NSTimer *myTimer; 

-(void)viewDidAppear:(BOOL)animated {    
   myTimer = [NSTimer scheduledTimerWithTimeInterval:26.0
        target:self
        selector:@selector(sendRequestToGetData:)
        userInfo:nil
        repeats:YES];
}

- (void)viewDidDisappear:(BOOL)animated{
   [myTimer invalidate];
   myTimer=nil;
}