[英]Trying to Save/Load Array Data to Plist
我一直在逐步学习Objective C和iPhone SDK,而我目前的项目涉及构建一个存储数字数据(体育数据)的应用程序。 这主要是出于学习目的,因为有多个应用程序执行相同的操作。 无论如何,我遇到了一些障碍。 我的意图是在表中存储一个玩家列表,并允许用户添加其他玩家。
目前,我有一个按钮,当按下该按钮时,“忍者”将添加到表格中。 我还启用了表格中的删除功能。 不幸的是,我似乎无法弄清楚如何从plist中保存和加载数据。 我遵循了各种教程和指南,但是我无法弄清楚发生了什么。 我的怀疑是我正在从一个空数组中加载数据并添加到该数组中,但是涉及数据的数组是与plist分离的数组。 不幸的是,我对此感到迷茫。
每当我切换视图时,阵列中的数据都会被擦除。 但是,我注意到,如果我离开然后再回来,数据仍然保留,但是如果我离开很长一段时间,离开并重新启动iphone等,数据就不会保留。即使对于我尚未使用过的应用,这似乎也会发生保存。 这是否只是iPhone保留数据的功能,以防用户意外退出程序?
希望我能切实地解释我的问题。 TL:DR版本:我想将数据添加到数组,将其保存到plist,并在屏幕上出现数组时从plist重新加载数据。 下面的代码正在尝试完成此操作,但未成功。
谢谢
#import "RootViewController.h"
#import "NewPlayer.h"
#import "OptionsMenu.h"
@implementation RootViewController
@synthesize createdPlayers;
@synthesize listOfPlayers;
-(NSString *) pathOfFile{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentFolder = [paths objectAtIndex:0];
return [documentFolder stringByAppendingFormat:@"myfile.plist"];
}
-(void)applicationWillTerminate:(NSNotification*)notification{
NSMutableArray *array = [[NSMutableArray alloc]init];
[array writeToFile: [self pathOfFile] atomically:YES];
}
- (void)viewDidLoad
{
NSString *filePath = [self pathOfFile];
if ([[NSFileManager defaultManager]fileExistsAtPath:filePath]) {
NSArray *array = [[NSArray alloc]initWithContentsOfFile:filePath];
listOfPlayers.array = [array objectAtIndex:0];
[array release];
}
UIApplication *app = [UIApplication sharedApplication];
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(applicationWillTerminate:) name:UIApplicationWillTerminateNotification object:app];
[super viewDidLoad];
listOfPlayers = [[NSMutableArray alloc] init];
}
-(IBAction)AddButtonAction:(id)sender{
[listOfPlayers addObject:@"Ninjas"];
[createdPlayers reloadData];
}
-(IBAction)switchView:(id)sender{
OptionsMenu *second = [[OptionsMenu alloc] initWithNibName:nil bundle:nil];
[self presentModalViewController:second animated:YES];
}
-(IBAction)newView:(id)sender{
NewPlayer *second = [[NewPlayer alloc] initWithNibName:nil bundle:nil];
[self presentModalViewController:second animated: YES];
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
}
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
}
- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
}
- (void)viewDidDisappear:(BOOL)animated
{
[super viewDidDisappear:animated];
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return [listOfPlayers count];
}
// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
// Configure the cell.
cell.textLabel.font = [UIFont fontWithName:@"Helvetica" size:15];
cell.textLabel.textColor = [UIColor whiteColor];
cell.textLabel.textAlignment = UITextAlignmentCenter;
NSString *cellValue = [listOfPlayers objectAtIndex:indexPath.row];
cell.textLabel.text = cellValue;
return cell;
}
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
return YES;
}
// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {
NSLog(@"delete section: %d rol: %d", [indexPath indexAtPosition:0], [indexPath indexAtPosition:1]);
[listOfPlayers removeObjectAtIndex:[indexPath indexAtPosition:1]];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
}
else if (editingStyle == UITableViewCellEditingStyleInsert)
{
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view.
}
}
-(void)tableView:(UITableView *)listOfPlayers moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath{
}
-(void)didReceiveMemoryWarning
{
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Relinquish ownership any cached data, images, etc that aren't in use.
}
- (void)viewDidUnload
{
[super viewDidUnload];
// Relinquish ownership of anything that can be recreated in viewDidLoad or on demand.
// For example: self.myOutlet = nil;
}
- (void)dealloc{
[createdPlayers release];
[listOfPlayers release];
[super dealloc];
}
@end
#import <UIKit/UIKit.h>
@interface RootViewController : UIViewController <UITableViewDelegate, UITableViewDataSource> {
IBOutlet UITableView* createdPlayers;
IBOutlet UIButton* superCat;
NSMutableArray *listOfPlayers;
}
@property(nonatomic, retain) IBOutlet NSObject *listOfPlayers;
-(NSString *) pathOfFile;
-(void)applicationWillTerminate:(NSNotification*)notification;
-(IBAction)AddButtonAction:(id)sender;
-(IBAction)switchView:(id)sender;
-(IBAction)newView:(id)sender;
@property (nonatomic, retain) UITableView* createdPlayers;
@end
代码更新12月20日:
-(NSString *) pathOfFile{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentFolder = [paths objectAtIndex:0];
return [documentFolder stringByAppendingFormat:@"myfile.plist"];
}
-(void)applicationWillTerminate:(NSNotification*)notification
{
[self.listOfPlayers writeToFile:[self pathOfFile] atomically:YES encoding:NSUTF8StringEncoding error:NULL];
}
- (void)viewDidLoad
{
self.listOfPlayers = [[NSMutableArray alloc] init];
NSString *filePath = [self pathOfFile];
if ([[NSFileManager defaultManager]fileExistsAtPath:filePath]) {
NSArray *array = [[NSArray alloc]initWithContentsOfFile:filePath];
self.listOfPlayers = array;
[array release];
}
UIApplication *app = [UIApplication sharedApplication];
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(applicationWillTerminate:) name:UIApplicationWillTerminateNotification object:app];
[super viewDidLoad];
}
我不知道plist。 但是您可以尝试使用NSData
NSArray *array;
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:array];
//Write data
[data writeToFile:filePath atomically:YES];
//Read data
NSFileManager *fileManager = [NSFileManager defaultManager];
NSData *oldData = [fileManager contentsAtPath:filePath];
NSArray *newArray = [NSKeyedUnarchiver unarchiveObjectWithData:oldData]
欢迎来到iOS编程世界。 这很有趣,但可能会令人沮丧,就像使用任何语言进行编程一样。 我感到你很痛苦。
我看到了很多东西:
在viewDidLoad中,似乎可以将文件读取到数组中的代码可以了,但是看上去好像您只是试图将此数组的第一行分配给listOfPlayers一样。 尝试:
self.listOfPlayers = array;
array是一个数组,您的listOfPlayers也是如此。 另外,使用self将确保使用合成的setter,从而在释放数组时保留listOfPlayers。
我相信在applicationWillTerminate中,您希望将listOfPlayers写入文件,但是您实际要做的是分配和初始化一个空数组,然后将THAT写入文件。 尝试:
-(void)applicationWillTerminate:(NSNotification*)notification { [self.listOfPlayers writeToFile: [self pathOfFile] atomically:YES]; }
我希望这有帮助!
您的viewDidLoad中似乎有问题
if ([[NSFileManager defaultManager]fileExistsAtPath:filePath]) {
NSArray *array = [[NSArray alloc]initWithContentsOfFile:filePath];
listOfPlayers.array = [array objectAtIndex:0];
.
.
}
.
.
.
listOfPlayers = [[NSMutableArray alloc] init];
您在分配listOfPlayers之前就已经对其进行了访问。 listOfPlayers.array也是错误的
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