将数据保存到一个视图控制器并在另一个视图控制器中显示

Question

我目前正在开发一个应用程序，需要有一个初始设置屏幕（名称，日期，存款金额和百分比）。我创建了一个视图控制器，它将添加并保存到核心数据。我也可以检索信息。

我接下来需要的是能够弹出到另一个视图控制器，并输入同一人的继续号码。每当我将数据输入到第二个视图控制器中时，它就会作为一个附加项目返回，就像它是一个新人一样。我需要一些帮助来弄清楚，因为我仍然是新的和学习。

下面是两个视图控制器的.h和.m文件。

ForexDetailViewController.h

#import <UIKit/UIKit.h> 

@interface ForexDetailViewController : UIViewController 
@property (weak, nonatomic) IBOutlet UITextField *nameTextField; 
@property (weak, nonatomic) IBOutlet UITextField *startamountTextField; 
@property (weak, nonatomic) IBOutlet UITextField *startmonthTextField; 
@property (strong, nonatomic) IBOutlet UITextField *startpercentTextField; 
@property (weak, nonatomic) IBOutlet UITextField *endmonth1year1TextField; 
@property (weak, nonatomic) IBOutlet UITextField *endpercentmonth1year1TextField; 

@property (strong) NSManagedObject *device; 
- (IBAction)cancel:(id)sender; 
- (IBAction)save:(id)sender; 
- (IBAction)textFieldReturn:(id)sender; 
- (IBAction)calcultae; 

@end 

ForexDetailViewController.m

#import "ForexDetailViewController.h" 

@interface ForexDetailViewController() 

@end 

@implementation ForexDetailViewController 

- (IBAction)textFieldReturn:(id)sender 
{ 
    [sender resignFirstResponder]; 
} 

@synthesize device; 

- (NSManagedObjectContext *)managedObjectContext { 
    NSManagedObjectContext *context = nil; 
    id delegate = [[UIApplication sharedApplication] delegate]; 
    if ([delegate performSelector:@selector(managedObjectContext)]) { 
     context = [delegate managedObjectContext]; 
    } 
    return context; 
} 

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil 
{ 
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; 
    if (self) { 
     // Custom initialization 
    } 
    return self; 
} 


- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view. 
    if (self.device) { 
     [self.nameTextField setText:[self.device valueForKey:@"name"]]; 
     [self.startamountTextField setText:[self.device valueForKey:@"startamount"]]; 
     [self.startmonthTextField setText:[self.device valueForKey:@"startmonth"]]; 
     [self.startpercentTextField setText:[self.device valueForKey:@"startpercent"]]; 
     [self.endmonth1year1TextField setText:[self.device valueForKey:@"endmonth1year1"]]; 
     [self.endpercentmonth1year1TextField setText:[self.device valueForKey:@"endpercentmonth1year1"]]; 
    } 

} 

- (void)didReceiveMemoryWarning 
{ 
    [super didReceiveMemoryWarning]; 
    // Dispose of any resources that can be recreated. 
} 


- (IBAction)cancel:(id)sender { 
    [self dismissViewControllerAnimated:YES completion:nil]; 
} 

- (IBAction)save:(id)sender { 
    NSManagedObjectContext *context = [self managedObjectContext]; 

    if (self.device) { 
     // Update existing device 
     [self.device setValue:self.nameTextField.text forKey:@"name"]; 
     [self.device setValue:self.startamountTextField.text forKey:@"startamount"]; 
     [self.device setValue:self.startmonthTextField.text forKey:@"startmonth"]; 
     [self.device setValue:self.startpercentTextField.text forKey:@"startpercent"]; 
     [self.device setValue:self.endmonth1year1TextField.text forKey:@"startpercent"]; 
     [self.device setValue:self.endpercentmonth1year1TextField.text forKey:@"endpercentmonth1year1"]; 

    } else { 
     // Create a new device 
     NSManagedObject *newDevice = [NSEntityDescription insertNewObjectForEntityForName:@"Calculations" inManagedObjectContext:context]; 
    [newDevice setValue:self.nameTextField.text forKey:@"name"]; 
    [newDevice setValue:self.startamountTextField.text forKey:@"startamount"]; 
    [newDevice setValue:self.startmonthTextField.text forKey:@"startmonth"]; 
    [newDevice setValue:self.startpercentTextField.text forKey:@"startpercent"]; 
    [newDevice setValue:self.endmonth1year1TextField.text forKey:@"endmonth1year1"]; 
     [newDevice setValue:self.endpercentmonth1year1TextField.text forKey:@"endpercentmonth1year1"]; 
} 

NSError *error = nil; 
// Save the object to persistent store 
if (![context save:&error]) { 
    NSLog(@"Can't Save! %@ %@", error, [error localizedDescription]); 
} 

[self dismissViewControllerAnimated:YES completion:nil]; 
} 


@end 

TimeLineViewController.h

#import <UIKit/UIKit.h> 

@interface TimeLineViewController : UIViewController 

@property (weak, nonatomic) IBOutlet UITextField *startamountTextField; 
@property (weak, nonatomic) IBOutlet UITextField *endmonth1year1TextField; 
@property (weak, nonatomic) IBOutlet UITextField *endpercentmonth1year1TextField; 

@property (strong) NSManagedObject *device; 
- (IBAction)cancel:(id)sender; 
- (IBAction)save:(id)sender; 
- (IBAction)textFieldReturn:(id)sender; 



@end 

TimeLineViewController.m

#import "TimeLineViewController.h" 

@interface TimeLineViewController() 

@end 

@implementation TimeLineViewController 

- (IBAction)textFieldReturn:(id)sender 
{ 
    [sender resignFirstResponder]; 
} 

@synthesize device; 

- (NSManagedObjectContext *)managedObjectContext { 
    NSManagedObjectContext *context = nil; 
    id delegate = [[UIApplication sharedApplication] delegate]; 
    if ([delegate performSelector:@selector(managedObjectContext)]) { 
     context = [delegate managedObjectContext]; 
    } 
    return context; 
} 

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil 
{ 
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; 
    if (self) { 
     // Custom initialization 
    } 
    return self; 
} 


- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view. 
    if (self.device) { 

     [self.startamountTextField setText:[self.device valueForKey:@"startamount"]]; 
     [self.endmonth1year1TextField setText:[self.device valueForKey:@"endmonthe1year1"]]; 
     [self.endpercentmonth1year1TextField setText:[self.device valueForKey:@"endpercentmonth1year1"]]; 

    } 

    } 

- (void)didReceiveMemoryWarning 
{ 
    [super didReceiveMemoryWarning]; 
    // Dispose of any resources that can be recreated. 
} 


- (IBAction)cancel:(id)sender { 
    [self dismissViewControllerAnimated:YES completion:nil]; 
} 

- (IBAction)save:(id)sender { 
    NSManagedObjectContext *context = [self managedObjectContext]; 

    if (self.device) { 
     // Update existing device 

     [self.device setValue:self.startamountTextField.text forKey:@"startamount"]; 
     [self.device setValue:self.endmonth1year1TextField.text forKey:@"endmonth1year1"]; 
     [self.device setValue:self.endpercentmonth1year1TextField.text forKey:@"endpercentmonth1year1"]; 


    } else { 
     // Create a new device 
     NSManagedObject *newDevice = [NSEntityDescription insertNewObjectForEntityForName:@"Calculations" inManagedObjectContext:context]; 

     [newDevice setValue:self.startamountTextField.text forKey:@"startamount"]; 
     [newDevice setValue:self.endmonth1year1TextField.text forKey:@"endmonth1year1"]; 
     [newDevice setValue:self.endpercentmonth1year1TextField.text forKey:@"endpercentmonth1year1"]; 

    } 

    NSError *error = nil; 
    // Save the object to persistent store 
    if (![context save:&error]) { 
     NSLog(@"Can't Save! %@ %@", error, [error localizedDescription]); 
    } 

    [self dismissViewControllerAnimated:YES completion:nil]; 
} 


@end 

ForexViewController.m

#import "ForexViewController.h" 
#import "ForexDetailViewController.h" 

@interface ForexViewController() 
@property (strong) NSMutableArray *devices; 
@end 

@implementation ForexViewController 

- (NSManagedObjectContext *)managedObjectContext { 
NSManagedObjectContext *context = nil; 
id delegate = [[UIApplication sharedApplication] delegate]; 
if ([delegate performSelector:@selector(managedObjectContext)]) { 
    context = [delegate managedObjectContext]; 
} 
return context; 
} 

- (id)initWithStyle:(UITableViewStyle)style 
{ 
    self = [super initWithStyle:style]; 
    if (self) { 
    // Custom initialization 
} 
     return self; 
} 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

// Uncomment the following line to preserve selection between presentations. 
// self.clearsSelectionOnViewWillAppear = NO; 

// Uncomment the following line to display an Edit button in the navigation bar for this view controller. 
// self.navigationItem.rightBarButtonItem = self.editButtonItem; 
} 

- (void)viewDidAppear:(BOOL)animated 
{ 
    [super viewDidAppear:animated]; 

// Fetch the devices from persistent data store 
    NSManagedObjectContext *managedObjectContext = [self managedObjectContext]; 
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Calculations"]; 
    self.devices = [[managedObjectContext executeFetchRequest:fetchRequest error:nil] mutableCopy]; 

    [self.tableView reloadData]; 
} 

- (void)didReceiveMemoryWarning 
{ 
    [super didReceiveMemoryWarning]; 
// Dispose of any resources that can be recreated. 
} 

#pragma mark - Table view data source 

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView 
{ 
// Return the number of sections. 
    return 1; 
} 

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{ 
// Return the number of rows in the section. 
    return self.devices.count; 
} 

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
static NSString *CellIdentifier = @"Cell"; 
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath]; 

// Configure the cell... 
NSManagedObject *device = [self.devices objectAtIndex:indexPath.row]; 
[cell.textLabel setText:[NSString stringWithFormat:@"%@", [device valueForKey:@"name"]]]; 
[cell.detailTextLabel setText:[device valueForKey:@"startamount"]]; 
[cell.detailTextLabel setText:[device valueForKey:@"startmonth"]]; 
[cell.detailTextLabel setText:[device valueForKey:@"startpercent"]]; 


return cell; 
} 


- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath 
    { 
    // Return NO if you do not want the specified item to be editable. 
    return YES; 
    } 


- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath 
    { 
    NSManagedObjectContext *context = [self managedObjectContext]; 

    if (editingStyle == UITableViewCellEditingStyleDelete) { 
    // Delete object from database 
     [context deleteObject:[self.devices objectAtIndex:indexPath.row]]; 

     NSError *error = nil; 
     if (![context save:&error]) { 
      NSLog(@"Can't Delete! %@ %@", error, [error localizedDescription]); 
      return; 
     } 

    // Remove device from table view 
     [self.devices removeObjectAtIndex:indexPath.row]; 
     [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; 
     } 
    } 

#pragma mark - Table view delegate 

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
// Navigation logic may go here. Create and push another view controller. 

} 


#pragma mark - Segue 

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender 
{ 
    if ([[segue identifier] isEqualToString:@"UpdateDevice"]) { 
     NSManagedObject *selectedDevice = [self.devices objectAtIndex:[[self.tableView indexPathForSelectedRow] row]]; 
     ForexDetailViewController *destViewController = segue.destinationViewController; 
     destViewController.device = selectedDevice; 
    } 
} 

@end 

Answer 1

哪里是你的代码，告诉您如何显示每个视图？

如果您是通过Storyboard segue完成此操作，则应在设置视图控制器时设置device属性。

目前，我没有看到self.device是如何为这两个视图控制器中的任何一个设置的，所以每次视图加载时，它都认为没有设备，因此创建一个新的记录。

一个简单的例子有一个故事板赛格瑞：

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender 
{ 
    if ([segue.identifier isEqualToString:@"changeDeviceSettings"]) { 
     SomeViewController *vc = segue.destinationViewController; 
     vc.device = selectedDeviceGoesHere; 
    } 
}