Question

可能重复：
Why does clearing NSUserDefaults cause EXC_CRASH later when creating a UIWebView?

**大家好，我在应用程序中有一个FAQ屏幕，这是webview，这个网页上有“Email Me”链接。单击此按钮时，将导航到Mail Composer。但app仍然在后台运行。现在点击返回最小化的应用程序并单击相同的FAQ链接，应用程序崩溃。这只发生在iOS 5.1中。以下是收到的日志：

-[__NSCFDictionary setObject:forKey:]: attempt to insert nil value (key: WebKitLocalStorageDatabasePathPreferenceKey)

我在“APPDelegate”文件中使用了以下代码

NSDictionary *settings = [[NSUserDefaults standardUserDefaults] dictionaryRepresentation];
    NSArray *keys = [settings allKeys];
    for (int i=0; i<[keys count]; i++)
    {
        NSString *key = [keys objectAtIndex:i];

        [[NSUserDefaults standardUserDefaults] removeObjectForKey:key];
    }
    [[NSUserDefaults standardUserDefaults] synchronize];

Answer 1

此崩溃不是因为版本更改。崩溃日志明确表示您正在尝试在Dictionary中插入nil值，这就是它崩溃的原因：

for (int i=0; i<[keys count]; i++)
{
     NSString *key = [keys objectAtIndex:i];
     if (key != nil)
          [[NSUserDefaults standardUserDefaults] removeObjectForKey:key];
}

尝试上面的代码并检查。

Answer 2

尝试以下代码。以这种方式删除NSUserDefaults中的任何内容

NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];



NSDictionary *userDefaultsDictionary = [userDefaults dictionaryRepresentation];

NSString *strWebDatabaseDirectory = [userDefaultsDictionary objectForKey:@"WebDatabaseDirectory"];

NSString *strWebKitLocalStorageDatabasePathPreferenceKey = [userDefaultsDictionary objectForKey:@"WebKitLocalStorageDatabasePathPreferenceKey"];



NSString *appDomain = [[NSBundle mainBundle] bundleIdentifier];

[[NSUserDefaults standardUserDefaults] removePersistentDomainForName:appDomain];



[userDefaults removePersistentDomainForName:[[NSBundle mainBundle] bundleIdentifier]];



if (strWebDatabaseDirectory) {

    [userDefaults setObject:strWebDatabaseDirectory forKey:@"WebDatabaseDirectory"];}

if (strWebKitLocalStorageDatabasePathPreferenceKey) {

    [userDefaults setObject:strWebKitLocalStorageDatabasePathPreferenceKey forKey:@"WebKitLocalStorageDatabasePathPreferenceKey"];}



[userDefaults synchronize];

希望它可以帮到你。

仅在iOS 5.1中崩溃

2 个答案: