我正在开发第一个应用程序，需要一些帮助。我已经阅读了大量关于SO的类似问题，但却没有得到任何结论。
我有一个简单的表视图控制器，它有一个加号按钮;按下时，会导致模态视图控制器要求用户将信息插入4个单独的字段中。当用户单击“保存”时，模式视图将被解除，并且信息将显示在表视图中，因为保存按钮调用NSManagedObject子类并通过Core Data保存它。
我正试图让它在用户键入第一个字段（名称）时，如果他们之前已经输入过该名称（如果他们使用save方法将其添加到Core Data），它会自动填充并显示一个隐藏的表视图，其中的条目与该名称匹配。我首先开始使用NSMutableArray，但感谢Jeff的评论，这不会持久保存数据，所以因为我已经拥有了Core Data功能，所以使用它更有意义。我正在编辑这篇文章，以包括我的核心数据目前的设置方式。
我基本上想用Core Data（http://www.dalmob.org/2011/03/01/alternative-autocomplete-uitextfield/）
来实现这个目标有一个信息实体与人物实体有关系。
- (IBAction)save:(id)sender
{
NSManagedObjectContext *context = [self managedObjectContext];
Information *information = [NSEntityDescription insertNewObjectForEntityForName:@"Information" inManagedObjectContext:context];
People *enteredPerson = (People *)[People personWithName:self.nameTextField.text inManagedObjectContext:context];
information.whichPerson = enteredPerson;
NSError *error = nil;
if (![context save:&error])
{
NSLog(@"Can't save! %@ %@", error, [error localizedDescription]);
}
[self dismissViewControllerAnimated:YES completion:nil];
}
enteredPerson调用People NSManagedObjectSubclass中的personWithName方法：
+ (People *)personWithName:(NSString *)name inManagedObjectContext:(NSManagedObjectContext *)context
{
People *people = nil;
// Creating a fetch request to check whether the name of the person already exists
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"People"];
request.predicate = [NSPredicate predicateWithFormat:@"name = %@", name];
NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES];
request.sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
NSError *error = nil;
NSArray *fetchedPeople = [context executeFetchRequest:request error:&error];
if (!fetchedPeople)
{
// Handle Error
}
else if (![fetchedPeople count])
{
// If the person count is 0 then let's create it
people = [NSEntityDescription insertNewObjectForEntityForName:@"People" inManagedObjectContext:context];
people.name = name;
}
else
{
// If the object exists, just return the last object .
people = [fetchedPeople lastObject];
}
return people;
}
基于创建NSFetchRequest的建议，我想知道最好的技术来做到这一点。
我是否在最后添加条目的保存方法中执行此操作：
// NSFetchRequest
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:context];
[fetchRequest setEntity:entity];
// Specifiy a predicate here if there are certain conditions your fetch must adhere to
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"ANY name CONTAINS[c] %@", self.nameTextField.text];
[fetchRequest setPredicate:predicate];
//NSError *error = nil;
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil) {
// Handle error
}
if ([fetchedObjects count] == 0)
{
// Add entry to results
}
我想要实现的是，从Core Data，当用户键入名称，引用核心数据（带有获取请求）时，如果该名称存在，则在用户开始输入时，填充下面的Table视图文本字段。
任何指导都将不胜感激。
编辑：我已经用一些其他代码更新了答案，几乎可以实现这一点。编辑：更多代码：
.h
中的属性声明@property (retain, nonatomic) IBOutlet UITextField *nameTextField;
@property (nonatomic, retain) NSString *substring;
@property (weak, nonatomic) IBOutlet UITableView *testTableView;
@property (nonatomic, retain) NSFetchedResultsController* autocompleteFetchedResultsController;
- (void)searchAutocompleteEntriesWithSubstring:(NSString *)substring;
viewDidLoad中
- (void)viewDidLoad
{
NSError *error;
if (![[self autocompleteFetchedResultsController] performFetch:&error])
{
NSLog(@"Unresolved error %@ %@", error, [error userInfo]);
exit(-1);
}
self.testTableView.delegate = self;
self.testTableView.dataSource = self;
self.testTableView.hidden = YES;
self.testTableView.scrollEnabled = YES;
self.nameTextField.delegate = self;
[super viewDidLoad];
}
保存方法
- (IBAction)save:(id)sender
{
NSManagedObjectContext *context = [self managedObjectContext];
Transaction *transaction = [NSEntityDescription insertNewObjectForEntityForName:@"Transaction" inManagedObjectContext:context];
People *enteredPerson = (People *)[People personWithName:self.nameTextField.text inManagedObjectContext:context];
transaction.whoFrom = enteredPerson;
NSError *error = nil;
if (![context save:&error])
{
NSLog(@"Can't save! %@ %@", error, [error localizedDescription]);
}
[self dismissViewControllerAnimated:YES completion:nil];
}
谢谢，
答案 0 :(得分：0)
使用Xcode片段库中的基本代码，您可以执行核心数据提取：
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"<#Entity name#>" inManagedObjectContext:<#context#>];
[fetchRequest setEntity:entity];
// Specifiy a predicate here if there are certain conditions your fetch must adhere to
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"<#Predicate string#>", <#Predicate arguments#>];
[fetchRequest setPredicate:predicate];
NSError *error = nil;
NSArray *fetchedObjects = [<#context#> executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil) {
// Handle error
}
将实体名称替换为存储NameTextField条目的名称。 fetchedObjects是一个数组，用于存储填充表格所需的信息。
显然，您还需要通过创建新实体并保存上下文，将任何新的NameTextField条目保存到核心数据。
答案 1 :(得分：0)
我有点工作了。我没有更新整个问题，而是将其留在那里供参考，因为我相信有人会遇到类似的情况。通过在我的视图控制器中使用FetchedResultsController对象，我现在得到一个名称列表，用于填充位于文本字段下方的表视图。
让我们看看一些代码：
- (NSFetchedResultsController *)autocompleteFetchedResultsController
{
NSManagedObjectContext *managedObjectContext = [self managedObjectContext];
if (_autocompleteFetchedResultsController != nil)
{
return _autocompleteFetchedResultsController;
}
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"People" inManagedObjectContext:managedObjectContext];
fetchRequest.entity = entity;
if ([self.substring length] > 0) {
NSPredicate *peoplePredicate = [NSPredicate predicateWithFormat:@"ANY name CONTAINS[c] %@", self.nameTextField.text];
[fetchRequest setPredicate:personPredicate];
}
NSSortDescriptor *sort = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:NO];
fetchRequest.sortDescriptors = [NSArray arrayWithObject:sort];
NSFetchedResultsController *theFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:nil cacheName:nil];
self.autocompleteFetchedResultsController = theFetchedResultsController; _autocompleteFetchedResultsController.delegate = self;
return _autocompleteFetchedResultsController;
}
- (void)viewDidLoad
{
NSError *error;
// I am performing the fetchHere and if there is an error, it will get logged.
if (![[self autocompleteFetchedResultsController] performFetch:&error])
{
NSLog(@"Unresolved error %@ %@", error, [error userInfo]);
exit(-1);
}
// Further code relating to tableview to make it hidden, etc
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
id sectionInfo = [[_autocompleteFetchedResultsController sections] objectAtIndex:section];
return [sectionInfo numberOfObjects];
}
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
self.testTableView.hidden = NO;
self.substring = self.nameTextField.text];
self.substring = [self.substring stringByReplacingCharactersInRange:range withString:self.substring];
[self searchAutocompleteEntriesWithSubstring:self.substring];
return YES;
}
#pragma mark UITableViewDataSource methods
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @"autocomplete cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
People *people = [self.autocompleteFetchedResultsController objectAtIndexPath:indexPath];
cell.textLabel.text = people.name;
return cell;
}
#pragma mark UITableViewDelegate methods
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *selectedCell = [tableView cellForRowAtIndexPath:indexPath];
self.nameTextField.text = selectedCell.textLabel.text;
}
所以这在某种程度上起作用。当我将光标放在nameTextField中时，它取消隐藏表视图，但它当前显示已输入的所有名称的名称。
我想要的是，正如我打字一样，桌子只能向我显示匹配的内容。
[self searchAutocompleteEntriesWithSubstring:substring];中的shouldChangeCharactersInRangeMethod正在调用我创建的自定义方法。
当我将此设置为NSMutableArray而不是使用Core Data时，它是下面的代码，但我不知道如何调整此代码来说，搜索核心数据并仅显示与我已经匹配的结果打字。
- (void)searchAutocompleteEntriesWithSubstring:(NSString *)substring {
self.autocompleteFetchedResultsController = nil;
[self autocompleteFetchedResultsController];
[self.testTableView reloadData];
}
我几乎就在那里 - 只需要一点推动就到那儿！
答案 2 :(得分：0)
我猜self.autocompleteUrls是你以前的NSMutableArray ...好的，你已经走了很长的路，现在看到autocompleteFetchedResultsController - ＆gt;这就是取物，并且条件if（_autocompleteFetchedResultsController！= nil）保护属性方法不会在每次U引用autocompleteFetchedResultsController时被调用。所以你应该做这样的事情：
- (void)searchAutocompleteEntriesWithSubstring:(NSString *)substring {
_autocompleteFetchedResultsController = nil;
[self autocompleteFetchedResultsController];
[self.testTableView reloadData];
}
如果你做了其他正确的事情应该是它......
您的cellFoRowAtIndexPath应如下所示：
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @"autocomplete cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
if(cell == nil){
cell = [[UITableViewCell alloc] initWithStyle:UITableViewStylePlain reuseIdentifier:CellIdentifier];
}
People *people = [self.autocompleteFetchedResultsController objectAtIndexPath:indexPath];
cell.textLabel.text = people.name;
return cell;
}