试图在viewController之间传递数据 [英] Trying to pass data between viewControllers
问题描述
我在NavigationController里面有一个4个viewController的序列，每个都从用户那里获取一些文本输入的文本框，存储在NSMutableDictionary中。
在下一代的委托之前，它将自己作为下一代的代表，它也通过了NSMutDict。
这个工作正常。
我不明白的是：
说我已经填写了VC1中的5个文本字段。然后我将自己设置为VC2的代表，将VC2的字典与输入数据一起传递到VC2。在VC2中，我填写另外4个文本字段，并将其添加到字典中。如果我决定我需要更改VC1中的某些东西，我点击后退按钮并修改数据。但是当我再次前进时，我会丢失我在VC2上输入的内容。
如何将字典传回给VC1加上附加的信息，以便当它转过来到VC2再次有它的一切吗？
代理（VC1）有一个方法来更新其字典与VC2中的字典。
我还通过在VC1中的prepareForSegue：方法中设置VCB中的backBarButtonItem来定制。
I认为我越来越近了...
我只能通过在VC2中设置一个leftBarButtonItem并使用它而不是默认的返回按钮来获得目标操作。
设置VC1（prepareForSegue :)中的后退按钮似乎不允许设置任何目标或操作。
$ b $我知道我不能在VC2中设置后退按钮，那我该怎么办？可以使用代理程序从VC2设置后退按钮的目标和动作吗？
我认为这可能与UINavigationBarDelegate有关，但我无法确定在哪里放什么。我尝试在VC2中设置它，但没有做任何事情。
TIA。
这里是相关的代码：
协议：
#import< Foundation / Foundation .h>
@protocol IAXAddNewUserDelegate< NSObject>
@required
- （void）updateNewUserDataWithData：（NSMutableDictionary *）newData;
@end
从VC1.h：
#importIAXAddNewUserDelegate.h
@interface IAXAddNewUser1：UITableViewController< UITextFieldDelegate，UIAlertViewDelegate，IAXAddNewUserDelegate>
@property（strong，nonatomic）NSManagedObjectContext * managedObjectContext;
@property（strong，nonatomic）User * selectedUser;
@property（强，非原子）用户* aNewUser;
@property BOOL isFirstUser;
- （void）updateNewUserDataWithData：（NSMutableDictionary *）newData;
@end
从VC1.m：
#pragma mark - Segues
- （void）prepareForSegue：（UIStoryboardSegue *）segue sender：（id）sender
{
if（[segue.identifier isEqualToString：@AddUser2]）{
IAXAddNewUser2 * addUser2VC = segue.destinationViewController;
addUser2VC.managedObjectContext = self.managedObjectContext;
addUser2VC.progressTotal = self.progressTotal;
addUser2VC.isFirstUser = self.isFirstUser;
addUser2VC.userData = self.userData;
addUser2VC.delegate = self;
if（self.selectedUser）{
addUser2VC.selectedUser = self.selectedUser;
}
self.title = @Step 1;
UIBarButtonItem * backButton = [[UIBarButtonItem alloc] initWithTitle：@Back
style：UIBarButtonItemStyleBordered
target：self
action：@selector（passDataBack :)]
self.navigationItem.backBarButtonItem = backButton;
}
}
#pragma mark - IAXAddNewUserDelegate方法
- （void）updateNewUserDataWithData：（NSMutableDictionary *）newData
{
self。 userData = newData;
NSLog（@Updated AddUserVC1）;
}
从VC2.m
$（$）$（$）$（$）$（$）$（$）$（$）
[self.delegate updateNewUserDataWithData：self.userData];
[self.navigationController popViewControllerAnimated：YES];
}
所有其他词典的词典，尝试使用单身人士。你可以在这里看到一个例子： http://stackoverflow.com/a/9690731/542400
另外，这里有一些代码：
MainDictionary.h
@interface MainDictionary：NSObject {
NSMutableDictionary * dictionary;
}
+（MainDictionary *）sharedDictionary;
- （NSString *）getStringForKey：（NSString *）string;
- （void）setString：（NSString *）string forKey：（NSString *）键;
@end
MainDictionary.m
#importMainDictionary.h
static MainDictionary * sharedDictionary;
@implementation MainDictionary
- （id）init {
self = [super init];
dictionary = [[NSMutableDictionary alloc] init];
//如果你想添加任何初步到字典，在这里做
return self;
}
+（MainDictionary *）sharedDictionary {
static dispatch_once_t onceToken;
dispatch_once（& onceToken，^ {
sharedDictionary = [[self alloc] init];
}）;
return sharedDictionary;
}
- （NSString *）getStringForKey：（NSString *）string {
return [dictionary objectForKey：string];
}
- （void）setString：（NSString *）string forKey：（NSString *）key {
[dictionary setValue：string forKey：key];
}
@end
现在#import MainDictionary.h和任何时间您要访问或设置该字典中的值（在本示例中，当您的textField结束编辑时），请执行以下操作：
- （void）textFieldDidEndEditing：（UITextField *）textField {
if（textField == textField1）{
[[MainDictionary sharedDictionary] setString：textField.text forKey：@textField1];
}
}
或：
- （void）viewWillAppear {
textField1.text = [[MainDictionary sharedDictionary] getStringForKey：@textField1];
[super viewWillAppear：YES];
}
在每个VC中实现这一点，你很好去。 p>
I have a sequence of 4 viewControllers inside a NavigationController, each grabs a few textFields of input from the user which are stored in a NSMutableDictionary.
Each of the VC's set's itself up as the delegate of the nextVC before it segues, it also passes the NSMutDict along.
This works fine.
What I don't understand is this:
Say I have filled in the 5 textFields in VC1. Then I set myself as the delegate of VC2, pass VC2 the dictionary with the input data and segue to VC2. In VC2 I fill in another 4 textFields and add these to the dictionary. If I then decide I need to change something in VC1 I tap the back button and amend the data. But when I go forwards again I lose the stuff I input on VC2.
How do I pass the dictionary back to VC1 with the added info so that when it gets passed forwards to VC2 again it has everything in it?
The delegate (VC1) has a method to update its dictionary with the dictionary in VC2.
I have also customised the backBarButtonItem in VC2 by setting it in the prepareForSegue: method in VC1.
I think I'm getting close but...
I can only get the target actions to work by setting a leftBarButtonItem in VC2 and using that instead of the default back button.
Setting the back button in VC1 (prepareForSegue:) doesn't seem to allow any target or action to be set.
I know I can't set the back button in VC2, so what can I do? Can I set the target and action of the back button from VC2 using the delegate?
I think it may be something to do with UINavigationBarDelegate but I can't figure out where to put what with that. I tried setting it up in VC2 but it didn't do anything.
TIA.
Here's the relevant code:
Protocol:
#import <Foundation/Foundation.h>
@protocol IAXAddNewUserDelegate <NSObject>
@required
- (void)updateNewUserDataWithData: (NSMutableDictionary *)newData;
@end
From VC1.h:
#import "IAXAddNewUserDelegate.h"
@interface IAXAddNewUser1 : UITableViewController <UITextFieldDelegate, UIAlertViewDelegate, IAXAddNewUserDelegate>
@property (strong, nonatomic) NSManagedObjectContext *managedObjectContext;
@property (strong, nonatomic) User *selectedUser;
@property (strong, nonatomic) User *aNewUser;
@property BOOL isFirstUser;
- (void)updateNewUserDataWithData: (NSMutableDictionary *)newData;
@end
From VC1.m:
#pragma mark - Segues
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:@"AddUser2"]) {
IAXAddNewUser2 *addUser2VC = segue.destinationViewController;
addUser2VC.managedObjectContext = self.managedObjectContext;
addUser2VC.progressTotal = self.progressTotal;
addUser2VC.isFirstUser = self.isFirstUser;
addUser2VC.userData = self.userData;
addUser2VC.delegate = self;
if (self.selectedUser) {
addUser2VC.selectedUser = self.selectedUser;
}
self.title = @"Step 1";
UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:@"Back"
style:UIBarButtonItemStyleBordered
target:self
action:@selector(passDataBack:)];
self.navigationItem.backBarButtonItem = backButton;
}
}
#pragma mark - IAXAddNewUserDelegate Methods
- (void)updateNewUserDataWithData: (NSMutableDictionary *)newData
{
self.userData = newData;
NSLog(@"Updated AddUserVC1");
}
From VC2.m
-(void)passDataBack:(id)sender
{
NSLog(@"Sending Data Back to VC1");
[self.delegate updateNewUserDataWithData:self.userData];
[self.navigationController popViewControllerAnimated:YES];
}
If you're updating all the dictionaries from all the other dictionaries, try using a singleton. You can see an example here: http://stackoverflow.com/a/9690731/542400
Also, here's some code:
MainDictionary.h
@interface MainDictionary : NSObject{
NSMutableDictionary *dictionary;
}
+(MainDictionary *)sharedDictionary;
-(NSString *)getStringForKey:(NSString *)string;
-(void)setString:(NSString *)string forKey:(NSString *)key;
@end
MainDictionary.m
#import "MainDictionary.h"
static MainDictionary *sharedDictionary;
@implementation MainDictionary
-(id)init{
self = [super init];
dictionary = [[NSMutableDictionary alloc] init];
// if you want to add anything preliminary to the dictionary, do it here
return self;
}
+(MainDictionary *)sharedDictionary{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
sharedDictionary = [[self alloc] init];
});
return sharedDictionary;
}
-(NSString *)getStringForKey:(NSString *)string{
return [dictionary objectForKey:string];
}
-(void)setString:(NSString *)string forKey:(NSString *)key{
[dictionary setValue:string forKey:key];
}
@end
Now #import MainDictionary.h, and any time you want to access or set values in that dictionary (in this example, when your textFields end editing), just do this:
-(void)textFieldDidEndEditing:(UITextField *)textField{
if(textField == textField1){
[[MainDictionary sharedDictionary] setString: textField.text forKey:@"textField1"];
}
}
or:
-(void)viewWillAppear{
textField1.text = [[MainDictionary sharedDictionary] getStringForKey:@"textField1"];
[super viewWillAppear:YES];
}
Implement this in each VC, and you're good to go.
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