Question

我在VC中有textview。使用nsuserdefaults保存此textview并稍后获取。在VC1中我得到了保存的textview并在UITableView中显示。但是当我启动应用程序时，它会自动在索引0中显示“null”文本。

VC：

-(void)save:(id)sender{

   NSUserDefaults *userData1 = [NSUserDefaults standardUserDefaults];
    [userData1 setObject:textView.text forKey:@"savetext"];
    [userData1 synchronize];
}

VC1：

-(void) viewWillAppear:(BOOL)animated{

    [super viewWillAppear:animated];

     // textArray=[[NSMutableArray alloc]init];

    txt=[[UITextView alloc]initWithFrame:CGRectMake(0, 0, 320, 400)];

    NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
    // getting an NSString
     NSString *savedValue = [prefs stringForKey:@"savetext"];

    NSLog(@"saved is %@",savedValue);

    txt.text = [NSString stringWithFormat:@"%@", savedValue];

    NSLog(@"text.txt is %@", txt.text);

    MyAppDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];

  if(![MyAppDelegate.textArray containsObject:txt.text]){
        [MyAppDelegate.textArray addObject:txt.text];
    }

   NSUserDefaults *userData1 = [NSUserDefaults standardUserDefaults];
    [userData1 setObject:MyAppDelegate.textArray forKey:@"save"];
    [userData1 synchronize];

}

UITableView使用数组显示文本值：

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

    NSMutableArray* myMutableArrayAgain = [NSMutableArray arrayWithArray:[[NSUserDefaults standardUserDefaults] objectForKey:@"save"]];

     NSLog(@"array is %@",myMutableArrayAgain);

     return [myMutableArrayAgain count];

  }


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    NSMutableArray* myMutableArrayAgain = [NSMutableArray arrayWithArray:[[NSUserDefaults standardUserDefaults] objectForKey:@"save"]];

    NSLog(@"mycell is %@",myMutableArrayAgain);

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    NSLog(@"cell is %@",cell);

    if (cell == nil) {

        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];

        NSLog(@"cell inside is %@",cell);

    }

 // Configure the cell...
    cell.textLabel.text = [myMutableArrayAgain objectAtIndex:indexPath.row];
    [cell.textLabel setFont:[UIFont fontWithName:@"Arial-BoldMT" size:14]];
    cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;

    return cell;

}

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Answer 1

这都是因为某些地方的代码错误：

1）带有数组的Nsmutable数组是错误的： - 因为userdefaults返回一个字符串。所以这样做： -

 NSUserDefaults *userData1 = [NSUserDefaults standardUserDefaults];
    NSMutableArray* myMutableArrayAgain = [NSMutableArray arrayWithObject:[userData1 valueForKey:@"savetext"]];

2）在VC中，你在“savetext”中保存key的值，但是在VC1中你要将值检索为“save”，所以改变它，它已在上面的代码中完成。

//以上2点可以解决你的问题，但我会说不要这样编码，因为它会消耗更多的内存，并会删除代码的整洁。您所做的代码可以非常有效的方式完成。我告诉你。

//首先使用View控制器VC并将IBAction添加到按钮和textView或textField中。在VC中写这段代码： -

.h文件

@interface demoViewController : UIViewController{
    IBOutlet UITextField *txt1;
}

-(IBAction)getData:(id)sender;

.m文件

//首先包含您要重定向的下一个控制器的头文件，假设XYZ

#import XYZ.h

-(IBAction)getData:(id)sender{
    NSUserDefaults *userData1 = [NSUserDefaults standardUserDefaults];
    [userData1 setObject:txt1.text forKey:@"savetext"];
    demoViewController1 *demo=[[demoViewController1 alloc]initWithNibName:@"demoViewController1" bundle:nil];
    [self.navigationController pushViewController:demo animated:NO];
}

//在ViewDisLoad或ViewDidAppear上选择第二个控制器IN taht

//获取全局MuttableArray

NSMutableArray *myMutableArrayAgain;

//我在ViewDidload上编写此代码，在此处分配数组，因为需要分配MutableObject

 NSUserDefaults *userData1 = [NSUserDefaults standardUserDefaults];
    myMutableArrayAgain=[[NSMutableArray alloc]init];
    [myMutableArrayAgain addObject: [userData1 valueForKey:@"savetext"]];

//现在查看表格方法

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

    return [myMutableArrayAgain count];

}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    NSLog(@"cell is %@",cell);

    if (cell == nil) {

        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];

        NSLog(@"cell inside is %@",cell);    
    }

    // Configure the cell...
    cell.textLabel.text = [myMutableArrayAgain objectAtIndex:indexPath.row];
    [cell.textLabel setFont:[UIFont fontWithName:@"Arial-BoldMT" size:14]];
    cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
    return cell;
}

//以这种方式应用，您可以用更少的代码和更好的方式完成这些工作。

UITableView单元格在索引0中显示“null”值

1 个答案: