归档数据，然后将其加载到 viewdidload

Posted 2023-03-07

【中文标题】归档数据，然后将其加载到 viewdidload

【英文标题】：Archiving data and then loading it on viewdidload

【发布时间】：2014-03-20 16:05:51

【问题描述】：

我正在学习 Objective-C 教程，在这项任务中，我必须制作一个地址簿样式的应用程序，在按下按钮后存储联系人详细信息，然后在下一次加载时恢复它们。

无法弄清楚为什么文本似乎没有被保存 - 所以下次我在模拟器中加载应用程序时显然不会加载。

[super viewDidLoad];

    NSFileManager *filemgr;
    NSString *documentsDirectory;
    NSArray *directoryPaths;

    filemgr =[NSFileManager defaultManager];
    directoryPaths = NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES);

    documentsDirectory =[directoryPaths objectAtIndex:0];

    filePath =[[NSString alloc]initWithString:[documentsDirectory stringByAppendingPathComponent:@"userInfo.dat"]];

    if ([filemgr fileExistsAtPath:filePath])
    
        NSMutableArray *userData;
        userData =[NSKeyedUnarchiver unarchiveObjectWithFile:filePath];

        txtFirstName.text =[userData objectAtIndex:0];
        txtLastName.text =[userData objectAtIndex:1];
        txtEmail.text =[userData objectAtIndex:2];
        txtPhone.text =[userData objectAtIndex:3];
        NSLog(@"File Has Been loaded");
    else
    
        NSLog(@"Error.");
    




- (IBAction)btnSaveDetails:(id)sender 
    NSMutableArray *contactDetails;
    contactDetails =[[NSMutableArray alloc]init];
    [contactDetails addObject:txtFirstName.text];
    [contactDetails addObject:txtLastName.text];
    [contactDetails addObject:txtEmail.text];
    [contactDetails addObject:txtPhone.text];

    [NSKeyedArchiver archiveRootObject:contactDetails toFile:filePath];

    NSLog(@"File Saved");

提前致谢

【问题讨论】：

您实际上并没有将 keyedarchiver 返回的 NSData 写入文件

【参考方案1】：

你试过了吗？

-(id)viewDidLoad

        NSMutableArray * userData = [[NSMutableArray alloc] init];

        NSData * downloadedData = [[NSData alloc] initWithContentsOfFile: [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/userInfo.plist"]];

        if (downloadedData.length)
            [userData setArray:[NSKeyedUnarchiver unarchiveObjectWithData:downloadedData]];

        NSLog(@"userData :%@", userData);

        downloadedData = nil;


-(IBAction)btnSaveDetails:(id)sender
    

   NSMutableArray * contactDetails =[[NSMutableArray alloc]init];

    [contactDetails addObject:txtFirstName.text];

    [contactDetails addObject:txtLastName.text];

    [contactDetails addObject:txtEmail.text];

    [contactDetails addObject:txtPhone.text];

    NSData * contactData = [NSKeyedArchiver archivedDataWithRootObject:contactDetails];

    [contactData writeToFile:[NSHomeDirectory() stringByAppendingPathComponent:@"Documents/userInfo.plist"] atomically:YES];

    contactData = nil;

【讨论】：

谢谢@Natarajan 我使用了你的代码，但仍然没有保存/加载

设置你的文件路径 = [documentsDirectory stringByAppendingPathComponent:@"userInfo.plist"];或 filePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/userInfo.plist"]

让它工作@Natarajan 谢谢。只需要弄清楚它是如何工作的！不完全理解 filePath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/userInfo.plist"];或：[contactData writeToFile:filePath atomically:YES];联系人数据 = 无；