Question

@ T-X解决了这个问题。我在代码中用“// SOLUTION”标记了这些更改!!!

我有以下问题，如果我使用了MostModalViewController，则NSMutableArray“projectsArray”会被重置。

这是我的代码：

这里是.h文件：

    // ViewController.h
#import <UIKit/UIKit.h>

@class AddProject;

@interface ViewController : UIViewController <UITableViewDelegate, UITableViewDataSource>
{
    IBOutlet UITableView *projectsTableView;
    UIAlertView *reallyDelete;

    BOOL candelButtonClicked;
    NSIndexPath *actualIndexPath;

    NSMutableArray *projectsArray;
    NSInteger ID;
    NSString *NAME;

    AddProject *addProject;
    **ViewController *viewContr; // SOLUTION**
}
- (IBAction)addNewProject:(id)sender;

- (void)addToTableView:(NSString *)projectName;

@property (nonatomic, retain) UIAlertView *reallyDelete;
@property (nonatomic) NSInteger cancelButtonIndex;

@property IBOutlet UITableView *projectsTableView;

@property (nonatomic, retain) AddProject *addProject;
**@property (nonatomic, retain) ViewController *viewContr; // SOLUTION**

@end

这里是.m文件：

    // ViewController.m
#import "ViewController.h"
#import "CustomTableCell.h"
#import "AddProject.h"

@interface ViewController ()

@end

@implementation ViewController

**@synthesize viewContr; // SOLUTION**

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    projectsArray = [[NSMutableArray alloc] init];
    ViewController *element = [[ViewController alloc] init];

    element->ID = 1;
    element->NAME = @"Demo project";
    NSLog(@"viewdidload");
    [projectsArray addObject:element];

    NSLog(@"1. Array length: %d", [projectsArray count]);
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    if ([projectsArray count] < 1) {
        NSLog(@"2. Array length: 0");
        return 0;
    } else {
        NSLog(@"2. Array length: %d", [projectsArray count]);
        return [projectsArray count];
    }
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    return 78;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *customTableCellIdentifier = @"CustomTableCell";

    CustomTableCell *cell = (CustomTableCell *)[tableView dequeueReusableCellWithIdentifier:customTableCellIdentifier];
    if (cell == nil)
    {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"CustomTableCell" owner:self options:nil];
        cell = [nib objectAtIndex:0];
    }

    ViewController *element = [[ViewController alloc] init];
    element = [projectsArray objectAtIndex:indexPath.row];
    cell.nameLabel.text = element->NAME;
    cell.prepTimeLabel.text = [NSString stringWithFormat:@"%i", element->ID];

    NSLog(@"3. Array length: %d", [projectsArray count]);

    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
}

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {

    if (editingStyle == UITableViewCellEditingStyleDelete) {
        // Delete the row from the data source

        reallyDelete = [[UIAlertView alloc] initWithTitle:@"Deleting" message:@"Do your really want to delete that row?" delegate:self cancelButtonTitle:@"No" otherButtonTitles:@"Yes", nil];
        [reallyDelete show];

        actualIndexPath = indexPath;
    }
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {

    if (buttonIndex != [reallyDelete cancelButtonIndex])
    {
        //If "Yes" clicked delete
        [projectsArray removeObjectAtIndex:actualIndexPath.row];
        NSLog(@"delete row");

        [self.projectsTableView deleteRowsAtIndexPaths:[NSMutableArray arrayWithObjects:actualIndexPath, nil] withRowAnimation:YES];
        [self.projectsTableView reloadData];
    }
}

#pragma mark Edit

- (IBAction)addNewProject:(id)sender {
    NSLog(@"4. Array length: %d", [projectsArray count]);

    AddProject *addProjectView = [[AddProject alloc] initWithNibName:@"AddProject" bundle:nil];
    NSLog(@"4.1 Array length: %d", [projectsArray count]);
    addProjectView.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
    NSLog(@"4.2 Array length: %d", [projectsArray count]);
    addProjectView.modalPresentationStyle = UIModalPresentationFormSheet;
    NSLog(@"4.3 Array length: %d", [projectsArray count]);
    **addProjectView.viewContr = self; // SOLUTION**
    [self presentModalViewController:addProjectView animated:YES];
    NSLog(@"4.4 Array length: %d", [projectsArray count]);
    addProjectView.view.superview.frame = CGRectMake(addProjectView.view.center.x/2.5, addProjectView.view.center.y/3, 800, 600);
    NSLog(@"4.5 Array length: %d", [projectsArray count]);
}

- (void)addToTableView:(NSString *)projectName
{
    NSLog(@"Project Array: %@", projectsArray);
    NSLog(@"addToTableView: %@", projectName);    
    NSLog(@"5. Array length: %d", [projectsArray count]);

    ViewController *element = [[ViewController alloc] init];

    element->ID = 2;
    element->NAME = projectName;

    [projectsArray addObject:element];

    NSLog(@"6. Array length: %d", [projectsArray count]);

    [self.projectsTableView reloadData];
    [self.projectsTableView setNeedsDisplay];
}

- (void)viewDidUnload
{
    [self setProjectsTableView:nil];
    self.projectsTableView = nil;
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return YES;
}

@end

这里是模态呈现视图的.h文件：

    // AddProject.h
#import <UIKit/UIKit.h>

@class ViewController;

@interface AddProject : UIViewController
{    
    IBOutlet UITextField *projectName;

    ViewController *viewContr;
}

- (IBAction)back:(id)sender;
- (IBAction)next:(id)sender;

@property (nonatomic, retain) ViewController *viewContr;

@end

模态呈现文件的.m文件：

    // AddProject.m
#import "AddProject.h"
#import "ViewController.h"

@interface AddProject ()

@end

@implementation AddProject

**@synthesize viewContr; // SOLUTION I've mist to synthesize it**

- (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 from its nib.
    **// SOLUTION no new allocation/init of ViewController**
}

- (IBAction)back:(id)sender
{
    [self dismissModalViewControllerAnimated:YES];
}

- (IBAction)next:(id)sender
{
    [viewContr addToTableView:projectName.text];
    [viewContr.projectsTableView reloadData];
    [viewContr.projectsTableView setNeedsDisplay];
    [self dismissModalViewControllerAnimated:YES];
}

- (void)viewDidUnload
{
    projectName = nil;
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return YES;
}

@end

我已经使用断点测试了代码，我可以在AddProject类“viewDidLoad”开始加载时找到问题。但我不知道为什么它会重置数组。

Answer 1

您应该在视图控制器的init方法中分配projectsArray，而不是在viewDidLoad中。 projectsArray = [[NSMutableArray alloc] init];在加载视图时分配了一个新的空数组。

Answer 2

您从ViewController屏幕导航到Add project屏幕。在Add Project屏幕中，您添加了一个新项目，并希望将此信息委托给您来自的ViewController屏幕。

现在，您正试图在ViewController中创建一个AddProject的实例，您在viewDidLoad方法中新实例化，并且在添加项目时，您通过以下方式提供信息：在其上调用- (void)addToTableView:(NSString *)projectName。这不起作用，因为 - 您分配的ViewController实例是一个新实例，而不是您导航的实例。当你alloc + init时，你得到一个新对象。因此，尽管您在addToTableView:上调用ViewController，但它不起作用，因为接收此消息的ViewController实例是新实例，而不是您导航的实例。< / p>

因此，您需要做的就是 - ViewController中有一个Add Project属性，您可以在导航之前设置该属性。然后您可以向此属性发送消息 - 如this成绩单中所述。

我想说 - 但是这件事有效，它提供了两个控制器之间的紧密耦合。

理想情况下，可以通过将ViewController（您从哪里导航）作为Add Project（您导航到的地方）的代表来完成此操作。然后Add Project可以通过类似- (void) addProjectController:(AddProjectViewController *) controller didAddProject:(NSString *) projectName的方式将添加的项目委托给它的委托。这提供了两个视图控制器之间的耦合丢失。要了解委派概念，请参阅Delegates and Datasources。或者，搜索其他堆栈溢出帖子。

Answer 3

好的，我的问题是通过stackoverflow聊天修复的。最终解决方案的提示来自用户@ T-X。我在我的问题中添加了代码中的提示。它们标有“// SOLUTION”。

在“添加项目视图”控制器的viewDidLoad方法中，删除该行 viewContr = [[ViewController alloc] init];。现在制作变量 viewContr类ViewController中的一个属性。也合成它。最后在- (IBAction)addNewProject:(id)sender方法中，在呈现控制器之前，执行- addProjectView.viewContr = self;。它将解决您的问题。

（引自chat.stackoverflow | @T-X）

调用modalViewController后NSMutableArray被重置

3 个答案: