代码在iOS5上工作正常，但在iOS4.3上没有

Question

我的代码在iOS5上工作正常但在iOS4.3上无效，我试图在导航控制器中显示带有进度条的加载屏幕，其中UIViewController为根视图。

问题是在iOS4.3上加载屏幕没有出现在正确的时间，它出现在第二个视图控制器的视图显示之前，然后很快消失。

以下是代码：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
    // Override point for customization after application launch.
    NSUserDefaults * standardUserDefaults = [NSUserDefaults standardUserDefaults];
    CGSize s = [[UIScreen mainScreen] bounds].size;
    [standardUserDefaults setObject:@"" forKey:@"display_resolution"];
    if((int)s.width == 640 && (int)s.height == 960)[standardUserDefaults setObject:@"@2x" forKey:@"display_resolution"];
    [standardUserDefaults synchronize];
    AC_Loading *loading = [[[AC_Loading alloc] initWithNibName:@"AC_Loading_iPhone" bundle:nil] autorelease];
    _navController0 = [[[UINavigationController alloc]initWithRootViewController:loading]autorelease];
    _navController0.navigationBar.hidden = YES;
    self.window.rootViewController = self.navController0;
    [self.window makeKeyAndVisible];
    return YES;
}

-

修改

我发现问题来自AC_Loading's代码，这个UIViewController必须显示一个加载屏幕，其中包含根据数据库统计信息更新的进度视图（我正在创建一个sqlite3数据库并更新如果需要并显示进度）。虽然在iOS5上使用此代码但它不在iOS4.x上我认为是因为viewDidAppear内部的循环（而pr＆lt; 1.0）：

#import "AC_Loading.h"
#import "database.h"

#import "AC_Menu.h"

@implementation AC_Loading
@synthesize logo;
@synthesize progress;
@synthesize informations;
@synthesize CLController;
float pr = 0.14;
int p = 0;
AC_Menu *menu;

NSUserDefaults *standardUserDefaults;
- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

- (void)viewDidLoad
{   
    [super viewDidLoad];
    standardUserDefaults = [NSUserDefaults standardUserDefaults];
    [standardUserDefaults setObject:@"NO" forKey:@"geoloc"];
    [standardUserDefaults synchronize];
    NSLog(@"%@", [NSString stringWithFormat:@"intro%@%@", [standardUserDefaults stringForKey:@"display_resolution"], @".jpg"]);
    [logo setImage:[UIImage imageNamed:[NSString stringWithFormat:@"intro%@%@", [standardUserDefaults stringForKey:@"display_resolution"], @".jpg"]]];
    //[progress setProgressTintColor:[UIColor purpleColor]];
    [progress setProgress:0.14];

    // Do any additional setup after loading the view, typically from a nib.

}

- (void)viewDidUnload
{
    [self setLogo:nil];
    [self setInformations:nil];
    [self setProgress:nil];
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:YES];
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:YES];
    database *DB = [[database alloc] init];
    [DB checkDB];
    NSString *message = @"Chargement des données";

    if([DB isCreated]== NO && [DB upToDate] == NO && sqlite3_open([[DB getDBPath:[NSString stringWithFormat:@"%@%@%@", @"Restaurant_V", [DB getVersion], @".sqlite" ]] UTF8String], [DB getDB]) == SQLITE_OK)
    {   
        message = @"Mise à jour des données";
        [DB setExecuting:YES];
        [NSThread detachNewThreadSelector:@selector(createDB) toTarget:DB withObject:nil];

        while([DB isExecuting]==YES)
        {
            if([DB isExecuting]==NO) break;
        }
        NSLog(@"Cas 1");
    }
    if([DB isCreated]== YES && [DB upToDate] == NO && sqlite3_open([[DB getDBPath:[NSString stringWithFormat:@"%@%@%@", @"Restaurant_V", [DB getVersion], @".sqlite" ]] UTF8String], [DB getDB]) == SQLITE_OK)
    {   
        [DB setExecuting:YES];
        [NSThread detachNewThreadSelector:@selector(updateDB:) toTarget:DB withObject:[DB getVersion]];
        while([DB isExecuting]==YES)
        {
            if([DB isExecuting]==NO) break;
        }
        NSLog(@"Cas 2");
    }
    int p = floor([progress progress]*100);
    while (pr<1.0)
    {
        p = floor(pr*100);
        if(p%14==0)
        {

            CFRunLoopRunInMode (kCFRunLoopDefaultMode, 0, true);
            [progress setProgress:pr];
            [informations setText:[NSString stringWithFormat:@"%@ (%d%@", message, p, @"%)"]];
        }
        pr += 0.000002;
    }
    [progress setProgress:1.0];
    [informations setText:[NSString stringWithFormat:@"%@ (100%@", message, @"%)"]];
    menu =
    [[[AC_Menu alloc] initWithNibName:@"AC_Menu_iPhone" bundle:nil] autorelease];
    [self.navigationController pushViewController:menu animated:YES];
    [DB release];
    CLController = [[CoreLocationController alloc] init];
    CLController.delegate = self;
    [CLController.locMgr startUpdatingLocation];
}

- (void)dealloc {
    [CLController release];
    [logo release];
    [informations release];
    [progress release];
    [super dealloc];
}