使用XCode 4.6、iOS6、CoreData、UITableViewController、NSFetchesResultsController
我想出了如何将以下日期输入NSDate变量：
todayDate
yesterdayDate
thisWeek
lastWeek
thisMonth
lastMonth
lastYear
现在，我想使用NSFetchedResultsController将数据放入基于上述变量中的数据的部分中。我想我将不得不做一些日期比较：
if ([date1 compare:date2] == NSOrderedDescending) {
NSLog(@"date1 is later than date2");
} else if ([date1 compare:date2] == NSOrderedAscending) {
NSLog(@"date1 is earlier than date2");
} else {
NSLog(@"dates are the same");
}
有些用户可能没有某些部分因此，我需要帮助在以下方法中放入什么来确定基于fetchRequest的节数：
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
我还需要知道如何将数据划分为numberOfRowsInSection:单元格，并将其显示为cellforRowAtIndexPath:单元格
一些代码示例会很好！谢谢
编辑
我还没有集成控制器，但下面是要获取的代码：
- (void) refreshTable {
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Meeting" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"lastmoddate" ascending:NO];
NSArray *sortDescriptors = [NSArray arrayWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
[self.managedObjectContext executeFetchRequest:fetchRequest onSuccess:^(NSArray *results) {
[self.refreshControl endRefreshing];
self.objects = results;
[self.tableView reloadData];
} onFailure:^(NSError *error) {
[self.refreshControl endRefreshing];
NSLog(@"An error %@, %@", error, [error userInfo]);
}];
以下是我获取日期的方法：
NSCalendar *cal = [NSCalendar currentCalendar];
NSDateComponents *components = [cal components:( NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit ) fromDate:[[NSDate alloc] init]];
[components setHour:-[components hour]];
[components setMinute:-[components minute]];
[components setSecond:-[components second]];
NSDate *today = [cal dateByAddingComponents:components toDate:[[NSDate alloc] init] options:0]; //This variable should now be pointing at a date object that is the start of today (midnight);
[components setHour:-24];
[components setMinute:0];
[components setSecond:0];
NSDate *yesterday = [cal dateByAddingComponents:components toDate: today options:0];
components = [cal components:NSWeekdayCalendarUnit | NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit fromDate:[[NSDate alloc] init]];
[components setDay:([components day] - ([components weekday] - 1))];
NSDate *thisWeek = [cal dateFromComponents:components];
[components setDay:([components day] - 7)];
NSDate *lastWeek = [cal dateFromComponents:components];
[components setDay:([components day] - ([components day] -1))];
NSDate *thisMonth = [cal dateFromComponents:components];
[components setMonth:([components month] - 1)];
NSDate *lastMonth = [cal dateFromComponents:components];
这就是我要做的。在该模型中创建一个核心数据模型和"用户"实体。我想你知道怎么做，但如果你不只是评论和解释。然后，只需像对待任何其他实体一样为您的实体创建一个自定义类，并为其提供lastmoddate NSDate属性，再加上我将添加一个creationDate属性，该属性将等于创建实体的确切日期和时间，这样您就可以将其用作每个UserEntity的标识符。对于要在UITableView中创建的每个部分，您还必须有一个单独的数组数组。当你向模型中添加一个用户实体时，设置属性，然后因为你说有些用户可能没有每个变量，所以把用户实体不需要的任何变量都设置为零。初始化数组时，只需将具有相应属性的用户实体添加到值中。最后，当您实现-（NSInteger）numberOfSectionsInTableView:（UITableView*）tableView时，您所要做的就是对数组进行计数。
以下是它应该是什么样子：
我将把代表每个用户的实体称为"UserEntity"（它的NSManagedObject类将具有相同的名称）。
以下代码位于您将用于创建和获取实体的任何类的头中——它可能与您用于显示UITableView的类相同。
@interface Class : UITableViewController {
NSManagedObjectContext *managedObjectContext;
NSMutableArray *arrayOfArrays;
}
@property (retain, nonatomic) NSManagedObjectContext *managedObjectContext;
@property (retain, nonatomic) NSMutableArray *arrayOfArrays;
下面的代码在实现中，您将使用哪个类来创建和获取实体——它可能与您用于显示UITableView的类相同。
//用于将UserEntity添加到模型（核心数据数据库）并设置其属性
- (UserEntity *)addUserEntityToModel {
UserEntity *myEnt = (UserEntity *)[NSEntityDescription insertNewObjectForEntityForName:@"UserEntity" inManagedObjectContext:self.managedObjectContext];
myEnt.creationDate = [NSDate date];
myEnt. lastmoddate = ...; //replace the '...' with however you get your date
//add any other values to the appropriate attributes here, any attributes that do not //pertain to the UserEntity simply ignore - they are automatically set to default when they //are created.
NSError *error = nil;
if(!managedObjectContext)
NSLog(@"managedObejctContext problem at ...");
else if (![managedObjectContext save:&error]) {
NSLog(@"context not saved!");;
} else
NSLog(@"context successfully saved.");
}
//用于获取用户实体的
- (NSMutableArray *)getFetchArray {
NSFetchRequest *request = [[NSFetchRequest alloc] init];
if(!managedObjectContext) {
NSLog(@"There is no managedObjectContext at getFetchArray");
}
NSEntityDescription *entity = [NSEntityDescription entityForName:@"UserEntity" inManagedObjectContext:managedObjectContext];
[request setEntity:entity];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"creationDate" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[request setSortDescriptors:sortDescriptors];
[sortDescriptors release];
[sortDescriptor release];
NSError *error = nil;
NSMutableArray *mutableFetchResults = [[managedObjectContext executeFetchRequest:request error:&error] mutableCopy];
if (mutableFetchResults == nil) {
NSLog(@"mutableFetchResults array is nil");
}
[request release];
return mutableFetchResults;
}
//设置阵列阵列
-(void)createArrayOfArrays {
NSMutableArray *fetchArray = [self getFetchArray];
NSMutableArray *todayDateArray = [[NSMutableArray alloc] init];
NSMutableArray *yesterdayDateArray = [[NSMutableArray alloc] init];
NSMutableArray *thisWeekArray = [[NSMutableArray alloc] init];
//... create an array for each section you want
for (UserEntity *ue in fetchArray) {
if(ue.lastmoddate) { //if the attribute is not nil
if(ue.lastmoddate isEqual todayDate)
[todayDateArray insertObject:ue atIndex:0];
else if (ue.lastmoddate isEqual yesterdayDate)
[yesterdayDateArray insertObject:ue atIndex:0];
// ... do this for every section array
}
}
arrayOfArrays = [[NSMutableArray alloc] initWithObjects:todayDateArray,yesterdayDateArray,...(the rest of the arrays created for each attribute), nil]
[todayDateArray release];
[yesterdayDateArray release];
// ... release all the arrays except arrayOfArrays and fetchArray
}
//设置managedObjectContext
- (id)init {
self = [super init];
if (self) {
AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];//what ever //the name of your appDel is.
NSManagedObjectContext *context = [appDelegate managedObjectContext];
self.managedObjectContext = context;
[self createArrayofArrays];//this first creates the arrayOfArrays and will set it //equal to anything that's saved in the database. If you add an entity you will need to update //it.
}
return self;
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
return arrayOfArrays.count;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return [[arrayOfArrays objectAtIndex:section] count];
}
//然后在表格视图中显示单元格
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (!cell) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
}
UserEntity *ent = (UserEntity *)[[arrayOfArrays objectAtIndex:indexPath.section] objectAtIndex:indexPath.row];
cell.accessoryType = UITableViewCellAccessoryBasic;
if(ent.lastmoddate) { //if lastmoddate is not nil
cell.textLabel.text = ent. lastmoddate;
} else {
NSLog(@"lastmoddate is nil at tableView: cellForRowAtIndexPath");
}
NSLog(@"tableView: cellForRowAtIndexPath called.");
return cell;
}