如何在iPhone中的应用程序启动时显示活动指示器

Question

我有一个应用程序，如果本地数据库中有数据，那么它将首先将其上传到服务器，然后再启动应用程序。我已在应用程序删除中编写了上传代码。我希望在上载时如何显示带有警报的活动指示器。 通常，很容易显示startAnimating和Stop，但是在这种情况下该怎么办？

   - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    


     [self copyDatabaseIfNeeded];


     NSMutableArray *tempArray = [[NSMutableArray alloc] init];
     self.coffeeArray = tempArray;
     [tempArray release];

     [Coffee checkData:[self getDBPath]];


  int mytestcount=rowCount;
        NSLog(@"My Test ROw Count IS %d",mytestcount);


    if (mytestcount=0) {


    NSLog("No Data To Upload");

    }


   else {


    [Coffee getInitialDataToDisplay:[self getDBPath]];

    [self uploadData];
   }


   [self.window addSubview:[navigationController view]];

       [self.window makeKeyAndVisible];

       return YES;
      }

Answer 1

显示UIActivityIndicator此操作需要把它的appDelegate的didFinishLaunchingWithOptions。 在不同的线程中执行上传，以便在执行操作时一直显示指示符。 更改如下：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    

        [self copyDatabaseIfNeeded];
        NSMutableArray *tempArray = [[NSMutableArray alloc] init];
        self.coffeeArray = tempArray;
        [tempArray release];
        [Coffee checkData:[self getDBPath]];
        int mytestcount=rowCount;
        NSLog(@"My Test ROw Count IS %d",mytestcount);
        if (mytestcount=0) {
            NSLog("No Data To Upload");
        }
       else {
            [Coffee getInitialDataToDisplay:[self getDBPath]];
            //Set activity indicator here and perform uploading in different thread so that indicator is displayed as long as operation is carried out.  

           [self performSelector:@selector(uploadData) withObject:nil afterDelay:0];
       }
       [self.window addSubview:[navigationController view]];
       [self.window makeKeyAndVisible];
       return YES;
      }

在警报中创建UIActivityIndicator并不困难。 您可以按照以下步骤进行操作：

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@" " message:@" " delegate:self cancelButtonTitle:nil otherButtonTitles:nil];
UIActivityIndicatorView *progress= [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(125, 50, 30, 30)];
progress.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhiteLarge;
[alert addSubview:progress];
[progress startAnimating];   
[alert show];  

您可以根据需要自定义警报 。
希望这可以帮助。