UIAlertView 仅在它被关闭后才显示 [英] UIAlertView showing up only after it's dismissed

问题描述

我已经尝试解决这个问题 2 天了，在有人发布另一个 stackoverflow 问题之前，我已经阅读了所有内容，但没有一个完全涵盖我的问题:

I've been trying to figure this out for 2 days now, and before anyone posts another stackoverflow question, I've read them all and none of them cover my problem exactly:

我有一个动态更新的 CoreData 应用程序.现在，在更新过程中，我希望弹出一个 UIAlertView，提示正在下载更新.

I have a CoreData app that updates dynamically. Now during the update I want an UIAlertView to pop up saying that an update is being downloaded.

这里是重要的代码:

AppDelegate:

- (void)applicationDidBecomeActive:(UIApplication *)application
{
    [myUpdater checkForUpdatesInContext:self.managedObjectContext];    
}

_

Updater Class:

- (void)checkForUpdatesInContext:(NSManagedObjectContext *)myManagedObjectContext
{
    [self loadUpdateTime];
    NSLog(@"Update start");
    NSDate *now = [NSDate dateWithTimeIntervalSinceNow:[[NSTimeZone localTimeZone] secondsFromGMT]];
    if ([now timeIntervalSinceDate:updateTime] < UPDATE_TIME_INTERVAL)
    {
        return;
    }
    [self showAlertViewWithTitle:@"Update"];
    ... //updating process
    [self.alertView dismissWithClickedButtonIndex:0 animated:YES];
    NSLog (@"Update done");
}

- (void) showAlertViewWithTitle:(NSString *)title
{
    self.alertView = [[UIAlertView alloc] initWithTitle:title message:@"Daten werden aktualisiert..." delegate:self cancelButtonTitle:nil otherButtonTitles:nil];
    ... //design the alertView
    [self.alertView show];
    NSLog (@"AlertView shows");
}

所以当我运行这个时会发生什么:

So here is what happens when I run this:

1. 启动图片展示
2. NSLog更新开始"触发
3. NSLogAlertView 显示"触发
4. 屏幕变暗但没有显示 AlertView
5. 更新正在运行
6. NSLog更新完成"触发
7. 启动图像消失，TabBarController 出现
8. UIAlertView 出现并立即消失，变暗的屏幕恢复正常

我希望发生的事情:

1. 启动图片
2. TabBarController 出现
3. 屏幕变暗和 UIAlertView 显示
4. 更新正在运行
5. UIAlertView 被关闭并且变暗的屏幕恢复正常

我知道它与 UI 线程和主线程以及其他东西有关.但我尝试了所有看起来的组合，但仍然不是预期的结果.请帮忙:)

I know it's something with the UI Thread and the main Thread and stuff.. But I tried every combination it seems but still not the expected result. Please help :)

HighlightsViewController Class:

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.updater = [[Updater alloc] init];
    [updater checkForUpdatesInContext:self.managedObjectContext];

    ... // other setup stuff nothing worth mentioning
}

这是调用 [super viewDidLoad] 的正确位置吗?因为它仍然不能像这样工作，当启动图像显示在屏幕上时，更新仍在完成.:-((我要放弃这个了..

Is this the right place to call [super viewDidLoad]? Because it still doesn't work like this, still the update is being done while the Launch Image is showing on the screen. :-(( I'm about to give this one up..

推荐答案

开始吧，在这个原型中，一切都按照你想要的方式工作.

Here you go, in this prototype things work exactly how you want them to.

标题:

#import <UIKit/UIKit.h>

@interface AlertViewProtoViewController : UIViewController
{

}

- (void) showAlertViewWithTitle:(NSString *)title;
- (void) checkForUpdatesInContext;
- (void) update;
- (void)someMethod;
- (void)someOtherMethod;

@end

#import "AlertViewProtoViewController.h"

类:

@implementation AlertViewProtoViewController

UIAlertView *alertView;
bool updateDone;
UILabel *test;
bool timershizzle;

#pragma mark - View lifecycle

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    self.view.backgroundColor = [UIColor yellowColor];

    UILabel *test = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 500, 500)];
    test.backgroundColor = [UIColor blueColor];
    [self.view addSubview:test];

    [self performSelector:@selector(checkForUpdatesInContext) withObject:nil afterDelay:0.0];
}


- (void)update
{
    //NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; //commented for auto ref counting
    NSLog(@"update start");
    //your update stuff
    NSLog(@"update end");
    updateDone = YES;
    //[pool release];
}

- (void)checkForUpdatesInContext//:(NSManagedObjectContext *)myManagedObjectContext
{
    //[self loadUpdateTime];

    NSLog(@"Update start");

    NSDate *now = [NSDate dateWithTimeIntervalSinceNow:[[NSTimeZone localTimeZone] secondsFromGMT]];
    //    if ([now timeIntervalSinceDate:updateTime] < UPDATE_TIME_INTERVAL)
    //    {
    //        return;
    //    }
    [self showAlertViewWithTitle:@"Update"];
    //[self setManagedObjectContext:myManagedObjectContext];

    [self performSelector:@selector(someMethod) withObject:nil afterDelay:0.0];

    [self performSelector:@selector(someOtherMethod) withObject:nil afterDelay:0.0];
}

-(void)someOtherMethod
{
    while (!updateDone) {
        //        NSLog(@"waiting...");
    }

    [alertView dismissWithClickedButtonIndex:0 animated:YES];
    NSLog (@"Update done");
    self.view.backgroundColor = [UIColor greenColor];
}

-(void)someMethod
{
    [self performSelectorInBackground:@selector(update) withObject:nil];
}

- (void) showAlertViewWithTitle:(NSString *)title
{
    alertView = [[UIAlertView alloc] initWithTitle:title message:@"Daten werden aktualisiert..." delegate:self cancelButtonTitle:nil otherButtonTitles:nil];
    alertView.frame = CGRectMake(100, 100, 200, 200);
    alertView.backgroundColor = [UIColor whiteColor];

    [self.view addSubview:alertView];

    [self.view setNeedsDisplay];

    NSLog (@"AlertView shows");
}

@end

您应该根据自己的目的进行调整，但它确实有效.

You should adjust were needed for your own purposes but it works.

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