ios - 核心数据，第一次运行时不会在 uitableview 中显示数据，第二次运行正常

Question

我想用 plist 文件中的数据填充 UITableView 到核心数据中

这让我很容易在以后的版本中更新 uitableview，然后我只需要在 plist life 中进行更改，核心数据会处理其余部分。请告诉我是否有更好的方法...

无论如何我在这里做的这个不能正常工作，在第一次运行时它填充了核心数据但是 UITableView 是空的，然后如果你完全关闭应用程序，也可以从多任务栏启动它再次向上它现在显示带有数据的 uitableview

在我的应用程序 delegate.h 中我有:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];

if ( ![userDefaults valueForKey:@"version"] )
{
    [self value1];
    [self value2];
    [self value3];
    [self value4];
    [self value5];
    [self value6];

    NSLog(@"running code");
    [[NSManagedObjectContext MR_defaultContext] MR_saveToPersistentStoreAndWait];

    // Adding version number to NSUserDefaults for first version:
    [userDefaults setFloat:[[[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleVersion"] floatValue] forKey:@"version"];
}

if ([[NSUserDefaults standardUserDefaults] floatForKey:@"version"] == [[[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleVersion"] floatValue] )
{
    /// Same Version so dont run the function
}
else
{
    [Hovedmenu MR_truncateAll];
    [BarneDaab MR_truncateAll];
    [Graviditeten MR_truncateAll];
    [MineSygedomme MR_truncateAll];
    [Fortalt MR_truncateAll];
    [Familien MR_truncateAll];

    [self value2];
    [self value3];
    [self value4];
    [self value5];
    [self value6];
    [self value1];

    [[NSManagedObjectContext MR_defaultContext] MR_saveToPersistentStoreAndWait];
    NSLog(@"running code agian");

    // Update version number to NSUserDefaults for other versions:
    [userDefaults setFloat:[[[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleVersion"] floatValue] forKey:@"version"];
}
}

和 value1 2 3 4 5 6 几乎完全相同，但来自不同的 plist，这里是例子

-(void)value1{
NSManagedObjectModel *mom = [self managedObjectModel];
NSDictionary *attrs = [[[mom entitiesByName] objectForKey:@"Hovedmenu"] attributesByName];
NSArray *keyedValues = [[NSArray alloc] initWithContentsOfFile:
                        [[NSBundle mainBundle] pathForResource:@"hovedMenu" ofType:@"plist"]
                        ];

for( NSDictionary *keyedValueDict in keyedValues ) {
    NSManagedObject *mObj = [NSEntityDescription insertNewObjectForEntityForName:@"Hovedmenu" inManagedObjectContext:[self managedObjectContext]];
    for (NSString *attribute in attrs) {
        id value = [keyedValueDict objectForKey:attribute];
        if (value == nil) {
            // Don't attempt to set nil, or you'll overwite values in self that aren't present in keyedValues
            continue;
        }
        NSAttributeType attributeType = [[attrs objectForKey:attribute] attributeType];
        if ((attributeType == NSStringAttributeType) && ([value isKindOfClass:[NSNumber class]])) {
            value = [value stringValue];
        } else if (((attributeType == NSInteger16AttributeType) || (attributeType == NSInteger32AttributeType) || (attributeType == NSInteger64AttributeType) || (attributeType == NSBooleanAttributeType)) && ([value isKindOfClass:[NSString class]])) {
            value = [NSNumber numberWithInteger:[value  integerValue]];
        } else if ((attributeType == NSFloatAttributeType) && ([value isKindOfClass:[NSString class]])) {
            value = [NSNumber numberWithDouble:[value doubleValue]];
        }
        [mObj setValue:value forKey:attribute];
        NSLog(@"Value %@ for Key %@", value, attribute);
    }

}
NSError *error;
[[self managedObjectContext] save:&error];
}

在我的 viewcontroller.h 中

-(void)viewWillAppear:(BOOL)animated{
[self.mainTableView reloadData];
[super viewWillAppear:animated];
NSError *error = nil;
if (![[self fetchedResultsController] performFetch:&error]) {
    // Update to handle the error appropriately.
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    exit(-1);  // Fail
}
}
- (NSFetchedResultsController *)fetchedResultsController {
if (_fetchedResultsController != nil) {
    return _fetchedResultsController;
}

    _fetchedResultsController = [Hovedmenu fetchAllGroupedBy:nil withPredicate:nil sortedBy:@"numberRow" ascending:YES delegate:self];

return _fetchedResultsController;

我也在用 MagicalRecord

Answer 1

最有可能的是，从我在这里的代码中可以看出，您用来获取 value1、value2 等值的上下文与 MagicalRecord 为您创建的上下文不同。如果您将该上下文更改为使用 MR_defaultContext，则可能会正确更新所有内容。