与实施核心数据混淆
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【中文标题】与实施核心数据混淆【英文标题】：confusion with implementing core data 【发布时间】：2013-07-24 05:26:45 【问题描述】：我是初学者，我正在尝试将我的应用程序迁移到 Core Data。我正在关注 Big Nerd Ranch 第 3 版书，但在那本书中，他们有一个商店类，其中包含一个项目类中的所有项目。我的应用程序不同。我有一个任务类，任务显示在 TableView 控制器中声明的任务数组中，如果你点击一个任务，它的详细信息会出现在一个详细视图控制器中。问题是，书上说我需要创建一个 NSManagedObjectContext、NSManagedObjectModel 和一个 NSPersistentStoreCoordinator，它们在商店中完成。我将在我的应用程序中的哪里声明这些？ TableView 控制器还是详细视图控制器？这是我的代码：
任务.h
#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>
@interface Tasks : NSManagedObject
@property (nonatomic) NSDateComponents *conversionInfo;
@property (nonatomic) NSTimeInterval dateCreated;
@property (nonatomic) double orderingValue;
@property (nonatomic, retain) NSString * taskName;
@property (nonatomic) double timeInterval;
@property (nonatomic, retain) NSString * timeIntervalString;
@property (nonatomic, retain) NSManagedObject *assetType;
@end
任务.m
@implementation Tasks
@dynamic conversionInfo;
@dynamic dateCreated;
@dynamic orderingValue;
@dynamic taskName;
@dynamic timeInterval;
@dynamic timeIntervalString;
@dynamic assetType;
-(void)awakeFromFetch
[super awakeFromFetch];
-(void)awakeFromInsert
[super awakeFromInsert];
NSTimeInterval t = [[NSDate date] timeIntervalSinceReferenceDate];
[self setDateCreated:t];
-(NSString *)timeIntervalString
NSCalendar *sysCalendar = [NSCalendar currentCalendar];
NSDate *date = [NSDate date];
NSDate *date1 = [NSDate dateWithTimeInterval:self.timeInterval sinceDate:date];
unsigned int unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit;
self.conversionInfo = [sysCalendar components:unitFlags fromDate:date toDate:date1 options:0];
if ([self.conversionInfo hour] == 0)
if ([self.conversionInfo minute] == 1)
self.timeIntervalString = [NSString stringWithFormat:@"%d MIN", [self.conversionInfo minute]];
else
self.timeIntervalString = [NSString stringWithFormat:@"%d MINS", [self.conversionInfo minute]];
else if ([self.conversionInfo hour] == 1)
if ([self.conversionInfo minute] == 0)
self.timeIntervalString = [NSString stringWithFormat:@"%d HR", [self.conversionInfo hour]];
else if ([self.conversionInfo minute] == 1)
self.timeIntervalString = [NSString stringWithFormat:@"%d HR %d MIN", [self.conversionInfo hour], [self.conversionInfo minute]];
else
self.timeIntervalString = [NSString stringWithFormat:@"%d HR %d MINS", [self.conversionInfo hour], [self.conversionInfo minute]];
else
if ([self.conversionInfo minute] == 0)
self.timeIntervalString = [NSString stringWithFormat:@"%d HRS ", [self.conversionInfo hour]];
else if ([self.conversionInfo minute] == 1)
self.timeIntervalString = [NSString stringWithFormat:@"%d HRS %d MIN", [self.conversionInfo hour], [self.conversionInfo minute]];
else
self.timeIntervalString = [NSString stringWithFormat:@"%d HRS %d MINS", [self.conversionInfo hour], [self.conversionInfo minute]];
return self.timeIntervalString;
@end
TableViewController.m
-(NSMutableArray *)taskArray
if (!taskArray)
taskArray = [NSMutableArray array];
return taskArray;
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
cellSubclassCell *cell = [tableView dequeueReusableCellWithIdentifier:@"UITableViewCell"];
if (!cell)
cell = [[cellSubclassCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"UITableViewCell"];
if([indexPath section] == 0)
cell.textLabel.text = [[[self.taskArray objectAtIndex:[indexPath row]] taskName] uppercaseString];
cell.imageView.image = [UIImage imageNamed:@"unchecked.png"];
cell.imageView.highlightedImage = [UIImage imageNamed:@"uncheckedhighlighted.png"];
[cell setAccessoryType:UITableViewCellAccessoryDisclosureIndicator];
[cell setBackgroundColor:[UIColor colorWithRed:236.0/255 green:240.0/255 blue:241.0/255 alpha:1.0f]];
cell.textLabel.textColor = baseColor;
NSString *detailText = [[self.taskArray objectAtIndex:[indexPath row]] timeIntervalString];
cell.detailTextLabel.text = detailText;
[[cell detailTextLabel] setFont:[UIFont fontWithName:@"Avenir-Black" size:12]];
[[cell textLabel] setFont:[UIFont fontWithName:@"AvenirNext-DemiBold" size:16]];
[cell.contentView setAlpha:1];
else if ([indexPath section] == 1)
cell.textLabel.text = [[[self.completedArray objectAtIndex:[indexPath row]] taskName] uppercaseString];
cell.imageView.image = [UIImage imageNamed:@"checked.png"];
[cell setAccessoryType:UITableViewCellAccessoryDisclosureIndicator];
[cell setBackgroundColor:[UIColor colorWithRed:236.0/255 green:240.0/255 blue:241.0/255 alpha:1.0f]];
cell.textLabel.textColor = baseColor;
NSString *detailText = [[self.completedArray objectAtIndex:[indexPath row]] timeIntervalString];
cell.detailTextLabel.text = detailText;
[[cell detailTextLabel] setFont:[UIFont fontWithName:@"Avenir-Black" size:12]];
[[cell textLabel] setFont:[UIFont fontWithName:@"AvenirNext-DemiBold" size:16]];
[cell.contentView setAlpha:0.5];
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(handlechecking:)];
//cell.contentView
[cell.imageView addGestureRecognizer:tap];
cell.imageView.userInteractionEnabled = YES;
return cell;
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
Tasks *task = [[Tasks alloc]init];
if (indexPath.section == 0)
task.taskName = [[self.taskArray objectAtIndex:[indexPath row]] taskName];
task.timeInterval = [[self.taskArray objectAtIndex:[indexPath row]] timeInterval];
task.dateCreated = [[self.taskArray objectAtIndex:[indexPath row]] dateCreated];
else if (indexPath.section == 1)
task.taskName = [[self.completedArray objectAtIndex:[indexPath row]] taskName];
task.timeInterval = [[self.completedArray objectAtIndex:[indexPath row]] timeInterval];
task.dateCreated = [[self.completedArray objectAtIndex:[indexPath row]] dateCreated];
DetailViewController *dvc = [[DetailViewController alloc]init];
[dvc setTestTask:task];
[[self navigationController] pushViewController:dvc animated:YES];
详细视图控制器.m
@interface DetailViewController ()
@end
@implementation DetailViewController
@synthesize testTask,timer,timerLabel, date1, alertView, components, timeRemaining;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self)
return self;
- (void)viewDidLoad
[super viewDidLoad];
[_timeLeft setFont:[UIFont fontWithName:@"BebasNeue" size:25]];
-(IBAction)startTimer:(id)sender
[sender setHidden:YES];
[pauseButton setHidden:NO];
[continueButton setHidden:NO];
gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
self.date1 = [NSDate dateWithTimeInterval:[testTask timeInterval] sinceDate:[NSDate date]];
timer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(timerAction:) userInfo:nil repeats:YES];
[timer fire];
-(void)viewWillAppear:(BOOL)animated
[super viewWillAppear:animated];
[timerLabel setFont:[UIFont fontWithName:@"BebasNeue" size:60]];
[[self navigationItem] setTitle:[testTask taskName]];
if (startButton.hidden == NO)
[pauseButton setHidden:YES];
[continueButton setHidden:YES];
else
[pauseButton setHidden:NO];
[continueButton setHidden:NO];
timeRemaining = [NSString stringWithFormat:@"%02d:%02d:%02d", [components hour], [components minute], [components second]];
timerLabel.text = timeRemaining;
[timerLabel setNeedsDisplay];
[self.view setNeedsDisplay];
-(void)viewWillDisappear:(BOOL)animated
[super viewWillDisappear:animated];
[testTask setTaskName:[testTask taskName]];
[testTask setTimeInterval:[testTask timeInterval]];
-(void)timerAction:(NSTimer *)t
NSDate *now = [NSDate date];
components = [gregorianCalendar components:NSHourCalendarUnit|NSMinuteCalendarUnit|NSSecondCalendarUnit fromDate:now toDate:self.date1 options:0];
timeRemaining = nil;
if([now compare:self.date1] == NSOrderedAscending)
timeRemaining = [NSString stringWithFormat:@"%02d:%02d:%02d", [components hour], [components minute], [components second]];
NSLog(@"works %@", timeRemaining);
else
timeRemaining = [NSString stringWithFormat:@"00:00:00"];
[self.timer invalidate];
self.timer = nil;
if (self.alertView == NULL)
self.alertView = [[UIAlertView alloc]initWithTitle:[testTask taskName] message:@"Time is up!" delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
[alertView performSelectorOnMainThread:@selector(show) withObject:nil waitUntilDone:YES];
NSLog(@"ended");
timerLabel.text = timeRemaining;
[timerLabel setNeedsDisplay];
[self.view setNeedsDisplay];
- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
self.alertView = NULL;
【问题讨论】：
【参考方案1】：您应该在您的AppDelgate.h 文件中声明NSManagedObjectContext、NSManagedObjectModel 和NSPersistentStoreCoordinator。
这三个对象大多需要在应用程序中只分配一次内存。
您需要在整个应用程序中使用NSManagedObjectContext 来保存/编辑/检索托管对象。
我的建议：
创建一个新项目，选择Master- Detail Application模板。检查Use Core data 选项。
您将在此新应用程序的AppDelegate.h 和AppDelegate.m 文件中获得有关Core Data 的所有模板代码，您可以将其复制/粘贴到您的应用程序中。
【讨论】：
我会使用 [[UIApplication sharedApplication]delegate] 来访问它们？ 您大部分时间都希望在其他视图控制器中使用 NSManagedObjectContext 对象，您可以在模板代码中看到它是 AppDelegate.h 中的一个属性。因此，要获得它的引用，您必须使用 AppDelegarte *appDelegate = [[UIApplication sharedApplication]delegate]; 来获取 AppDelegate 对象。然后你想要 NSManagedObjectContext 引用简单地做，appDelegate.managedObjectContext 我如何将tableview控制器中的数据源数组转换为核心数据？ AppDelegate 绝对是一个类，关于表视图控制器的数据源数组，您必须从 Core Data 获取数组项。如果您不熟悉 Core Data，我建议您阅读以下 Apple 文档：developer.apple.com/library/mac/#documentation/cocoa/Conceptual/…【参考方案2】：它们都是在 appDelegate 类中创建的。当您创建项目时，您选择核心数据选项和模型，并且为您创建所有 NSManagedObjectContext、NSManagedObjectModel 和 NSPersistentStoreCoordinator。它们是全球性的，您可以通过以下方式在任何地方访问它们：
[[UIApplication sharedApplication]delegate]
【讨论】：
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