我有几个CoreDataTableViewControllers,它们使用Paul Hegarty课程中的助手类。除了这一个,他们每个人都有效,我看不出有什么区别。
当表格首次出现时,它被正确填充并且当选择单元格时segue正确执行。但是当我点击后退按钮时,表格随处可见(null),(null)。
我已经尝试了我能想到的每个调用[self useDocument]的变体,但仍无济于事。有什么想法吗?提前谢谢。
//
// TeamTableViewController.m
//
#import "TeamTableViewController.h"
#import "iTrackAppDelegate.h"
#import "CoreDataTableViewController.h"
#import "SchoolRecords.h"
#import "ScheduleViewController.h"
@interface TeamTableViewController ()
@property NSInteger toggle;
@end
@implementation TeamTableViewController
@synthesize iTrackContext = _iTrackContext;
@synthesize schoolSelected = _schoolSelected;
-(void) setSchoolSelected:(SchoolRecords *)schoolSelected
{
_schoolSelected = schoolSelected;
}
-(void) setITrackContext:(NSManagedObjectContext *)iTrackContext
{
if(_iTrackContext != iTrackContext){
if (!iTrackContext) {
MyCoreDataHandler* cdh =
[(iTrackAppDelegate *) [[UIApplication sharedApplication] delegate] cdh];
_iTrackContext = cdh.context;
} else {
_iTrackContext = iTrackContext;
}
}
[self useDocument];
}
- (id)initWithStyle:(UITableViewStyle)style
{
self = [super initWithStyle:style];
if (self) {
// Custom initialization
}
return self;
}
- (void)setupFetchedResultsController // attaches an NSFetchRequest to this UITableViewController
{
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"SchoolRecords"];
// no predicate because we want ALL the Athletes
request.sortDescriptors = [NSArray arrayWithObjects:
[NSSortDescriptor sortDescriptorWithKey:@"schoolName" ascending:YES],
nil];
self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request
managedObjectContext:self.iTrackContext
sectionNameKeyPath:nil
cacheName:nil];
__block NSInteger myCount;
int64_t delayInSeconds = 5.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
[self.iTrackContext performBlock:^(void){NSError* requestError = nil;
myCount = [self.iTrackContext countForFetchRequest:request error:&requestError];
NSLog(@"In %@ and count of iTrackContext = %lu", NSStringFromClass([self class]),(unsigned long)myCount);
}];
if (!myCount || myCount == 0) {
[self displayAlertBoxWithTitle:@"No Teams" message:@"Have you added athletes yet? \nPlease go to Add Athletes" cancelButton:@"Okay"];
}
});
}
- (void)useDocument
{
if (self.iTrackContext) {
[self setupFetchedResultsController];
} else {
NSString* errorText = @"A problem arose opening the search results database of Athletes.";
[self displayAlertBoxWithTitle:@"File Error" message:errorText cancelButton:@"Okay"];
}
}
-(void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
if (!self.iTrackContext) {
MyCoreDataHandler* cdh =
[(iTrackAppDelegate *) [[UIApplication sharedApplication] delegate] cdh];
[self setITrackContext:cdh.context];
} else {
NSLog(@"In %@ of %@. Getting ready to call useDocument",NSStringFromSelector(_cmd), self.class);
[self useDocument];
}
}
- (void)viewDidLoad
{
[super viewDidLoad];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#pragma mark - Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// If divide into sections use line below otherwise return 1.
// return [[self.fetchedResultsController sections] count];
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Do not really need this with only one section, but makes code usable if add sections later.
return [[[self.fetchedResultsController sections] objectAtIndex:section] numberOfObjects];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @"teamInformation";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
SchoolRecords *schoolResults = [self.fetchedResultsController objectAtIndexPath:indexPath];
NSString* titleText = schoolResults.schoolName;
cell.textLabel.text = titleText;
cell.detailTextLabel.text = [NSMutableString stringWithFormat:@"%@, %@", schoolResults.schoolCity, schoolResults.schoolState];
return cell;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
}
# pragma navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
NSIndexPath *indexPath = [self.tableView indexPathForCell:sender];
[self setSchoolSelected:[self.fetchedResultsController objectAtIndexPath:indexPath]];
// be somewhat generic here (slightly advanced usage)
// we'll segue to ANY view controller that has a photographer @property
if ([segue.identifier isEqualToString:@"scheduleDetailSegue"]) {
// use performSelector:withObject: to send without compiler checking
// (which is acceptable here because we used introspection to be sure this is okay)
NSLog(@"Preparing to passing school with schoolID = %@", self.schoolSelected.schoolID);
[segue.destinationViewController convenienceMethodForSettingSchool:self.schoolSelected];
}
}
- (void) displayAlertBoxWithTitle:(NSString*)title message:(NSString*) myMessage cancelButton:(NSString*) cancelText
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:title
message:myMessage
delegate:nil
cancelButtonTitle:cancelText
otherButtonTitles:nil];
[alert show];
}
@end
答案 0 :(得分:1)
嗯,我不确定问题是什么。我最终删除了#34;违规" StoryBoard中的TableViewControllers并重新创建它们。这就是诀窍。回想起来,我想知道我是不是从tabViewController中指定了错误的segue类型。但是在我想到这种可能性之前我删除了它。