iOS-App退到桌面再切回App时请求中断

前几天发现App中有一种情况，就是当前接口正在请求，还没返回数据，这时退到桌面，再切回App的时候，这个请求会中断。

解决方法如下：

@interface AppDelegate ()
@property (nonatomic, unsafe_unretained) UIBackgroundTaskIdentifier taskId;
@property (nonatomic, strong) NSTimer *timer;
@end

- (void)applicationDidEnterBackground:(UIApplication *)application {
    self.taskId = [application beginBackgroundTaskWithExpirationHandler:^(void) {
        //当申请的后台时间用完的时候调用这个block
        [self endTask];
    }];
    
    self.timer =[NSTimer scheduledTimerWithTimeInterval:1.0f
                                                 target:self
                                               selector:@selector(longTimeTask:)
                                               userInfo:nil
                                                repeats:YES];
}

- (void) longTimeTask:(NSTimer *)timer{
    
    NSTimeInterval time =[[UIApplication sharedApplication] backgroundTimeRemaining];
    DebugNsLog(@"剩余时间 = %.02f Seconds", time);
  
}

#pragma mark - 停止timer
-(void)endTask
{

    if (_timer != nil||_timer.isValid) {
        [_timer invalidate];
        _timer = nil;
        
    
        [[UIApplication sharedApplication] endBackgroundTask:self.taskId];
        self.taskId = UIBackgroundTaskInvalid;
        
        DebugNsLog(@"停止timer");
    }
}

- (void)applicationWillEnterForeground:(UIApplication *)application {
    [self endTask];
}

代码转自文章：https://www.jianshu.com/p/1401a709a7c6