问题
My NSMutableArray is declared in my .h file like this
@property (strong, nonatomic) NSMutableArray * numbers;
How do I use the NSMutableArray to save the data that is inputed to save to NSUserDefaults
All help is appreciated
Thanks in advance
code in .h file
@property (retain, nonatomic) IBOutlet UITableView *myTableView;
@property (strong, nonatomic) NSMutableArray * numbers;
code in .m
@synthesize myTableView, numbers;
-(void) viewDidLoad
{
NSUserDefaults *defaults=[NSUserDefaults standardUserDefaults];
[defaults setObject:numbers forKey:@"numberArray"];
NSMutableArray *resultArray = [NSMutableArray arrayWithArray:[defaults objectForKey:@"numberArray"]];
[super viewDidLoad];
// instantiate our NSMutableArray
numbers = [[NSMutableArray alloc]initWithObjects:@"",@"", nil];
//Add a edit button
self.navigationItem.leftBarButtonItem = self.editButtonItem;
//Add the Add button
UIBarButtonItem * addButton = [[UIBarButtonItem alloc]
initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target: self action: @selector(insertNewObject)];
self.navigationItem.rightBarButtonItem = addButton;
}
-(void) didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
}
-(void)setEditing:(BOOL)editing animated:(BOOL)animated
{
[super setEditing:editing animated:animated];
[myTableView setEditing:editing animated:animated];
}
-(void) insertNewObject
{
//Display a UIAlertView
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Enter HomeWork" message: @"" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Ok", nil];
alert.alertViewStyle = UIAlertViewStylePlainTextInput;
[alert show];
}
#pragma mark - UITableView Datasource
-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
return numbers.count;
}
-(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];
}
cell.textLabel.text = [numbers objectAtIndex:indexPath.row];
return cell;
}
-(BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
return YES;
}
-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete)
{
//remove our NSMutableArray
[numbers removeObjectAtIndex:indexPath.row];
//remove from our tableView
[tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
}
}
#pragma mark - UITableView Delegate methods
#pragma mark - UIAlertViewDelegate Methods
-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
//Only perform the following actions if the user hits the ok button
if (buttonIndex == 1)
{
NSString * tmpTextField = [alertView textFieldAtIndex:0].text;
if(!numbers)
numbers = [[NSMutableArray alloc]init];
[numbers insertObject:tmpTextField atIndex:0];
NSIndexPath * indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
[self.myTableView insertRowsAtIndexPaths:@[indexPath]withRowAnimation:UITableViewRowAnimationAutomatic];
}
}
@end
Ok, in my app, there is a UITableView
when the user taps the "plus" button, a UIAlertView shows up with a UITextField, when the user types a word, the text goes to the UITableView, but when the user exits the app, the text is gone from the table. I want to save the text the user puts in, so when the user exits the app and comes back, i want the text to save. I want to save it with NSUserDefaults.
回答1:
//For saving
NSUserDefaults *defaults=[NSUserDefaults standardUserDefaults];
[defaults setObject:self.numbers forKey:@"numberArray"];
[defaults synchronize];
//For retrieving
NSMutableArray *resultArray = [NSMutableArray arrayWithArray:[defaults objectForKey:@"numberArray"]];
According to you scenario when you running application after exiting... you should in viewDidLoad check if the keyExists in the NSUserDefaults then retrieve the results in the array and show in the UITableView. For Saving the Data, it is good idea to listen to a notification when user minimize the app, just save the data into the defaults.
Here is the working code for your case
- (void)viewDidLoad{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
//Add a edit button
self.navigationController.navigationItem.leftBarButtonItem = self.editButtonItem;
// check here if key exists in the defaults or not, if yes the retrieve results in array
if([[NSUserDefaults standardUserDefaults] objectForKey:@"numberArray"] != nil) {
self.numbers = [NSMutableArray arrayWithArray:[[NSUserDefaults standardUserDefaults] objectForKey:@"numberArray"]];
}
//Register for the notification when user go to background or minimize the app, just save the array objects in the defaults
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(appWillGoToBackground:)
name:UIApplicationWillResignActiveNotification
object:[UIApplication sharedApplication]];
//Add the Add button
UIBarButtonItem * addButton = [[UIBarButtonItem alloc]
initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target: self action: @selector(insertNewObject)];
self.navigationController.navigationItem.rightBarButtonItem = addButton;
}
-(void)setEditing:(BOOL)editing animated:(BOOL)animated {
[super setEditing:editing animated:animated];
[self.myTableView setEditing:editing animated:animated];
}
-(void)appWillGoToBackground:(NSNotification *)note {
NSLog(@"terminate");
NSUserDefaults *defaults=[NSUserDefaults standardUserDefaults];
[defaults setObject:self.numbers forKey:@"numberArray"];
[defaults synchronize];
}
-(void)insertNewObject{
//Display a UIAlertView
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Enter HomeWork" message: @"" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Ok", nil];
alert.alertViewStyle = UIAlertViewStylePlainTextInput;
[alert show];
}
-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
//Only perform the following actions if the user hits the ok button
if (buttonIndex == 1)
{
NSString * tmpTextField = [alertView textFieldAtIndex:0].text;
if(!self. numbers){
self.numbers = [[NSMutableArray alloc]init];
}
[self.numbers insertObject:tmpTextField atIndex:0];
NSIndexPath * indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
[self.myTableView insertRowsAtIndexPaths:@[indexPath]withRowAnimation:UITableViewRowAnimationAutomatic];
}
-(NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
return self.numbers.count;
}
-(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];
}
cell.textLabel.text = [self.numbers objectAtIndex:indexPath.row];
return cell;
}
-(BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
return YES;
}
-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete)
{
//remove our NSMutableArray
[self.numbers removeObjectAtIndex:indexPath.row];
//remove from our tableView
[tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
}
}
来源：https://stackoverflow.com/questions/15396365/how-to-save-data-with-nsuserdefaults-using-data-from-nsmutablearray