iOS 專案一直在後臺執行

theFeng-發表於2014-11-19
iOS
我後來是這麼解決不知道行不行，可以長期的在後臺執行
首先我在xx-info.plist 裡的 "Required background modes" 里加入"App provides Voice over IP services"

然後在delegate里加入以下程式碼，原理是進入後臺時程式會在600秒那樣結束任務，我做的就是在結束任務前新開一個任務，再結束舊任務，這樣就一直的在後臺執行，希望可能幫助到更多的人，我也查了很久才找到這個方法的。


UIBackgroundTaskIdentifier backgroundTaskIdentifier;
02 UIBackgroundTaskIdentifier oldBackgroundTaskIdentifier;
03  
04 - (BOOL) isMultitaskingSupported{
05      
06     BOOL result = NO;
07      
08     if ([[UIDevice currentDevice]
09           
10          respondsToSelector:@selector(isMultitaskingSupported)]){ result = [[UIDevice currentDevice] isMultitaskingSupported];
11          
12     }
13      
14     return result;
15      
16 }
17  
18 - (void) timerMethod:(NSTimer *)paramSender{
19     count++;
20     if (count % 500 == 0) {       
21         UIApplication *application = [UIApplication sharedApplication];
22          
23         //開啟一個新的後臺
24          
25         backgroundTaskIdentifier = [application beginBackgroundTaskWithExpirationHandler:^{
26    
27         }];
28         //結束舊的後臺任務
29         [application endBackgroundTask:backgroundTaskIdentifier];
30         oldBackgroundTaskIdentifier = backgroundTaskIdentifier;
31     }
32     NSLog(@"%ld",count);
33 }
34 - (void)applicationDidEnterBackground:(UIApplication *)application
35 {
36     if ([self isMultitaskingSupported] == NO){
37          
38         return; }
39     //開啟一個後臺任務
40      
41     backgroundTaskIdentifier = [application beginBackgroundTaskWithExpirationHandler:^{       
42     }];
43     oldBackgroundTaskIdentifier = backgroundTaskIdentifier;
44     if ([self.myTimer isValid]) {
45         [self.myTimer invalidate];
46     }
47     self.myTimer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(timerMethod:) userInfo:nil repeats:YES];
48 }
49  
50 - (void)applicationWillEnterForeground:(UIApplication *)application
51 {
52     if (backgroundTaskIdentifier != UIBackgroundTaskInvalid){
53         [application endBackgroundTask:backgroundTaskIdentifier];
54         if ([self.myTimer isValid]) {
55             [self.myTimer invalidate];
56         }
57     }
58 }
59  
60 - (void)applicationWillEnterForeground:(UIApplication *)application
61 {
62     if (backgroundTaskIdentifier != UIBackgroundTaskInvalid){
63         [application endBackgroundTask:backgroundTaskIdentifier];
64         if ([self.myTimer isValid]) {
65             [self.myTimer invalidate];
66         }
67     }
68 }

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