试图在 viewControllers 之间传递数据 [英] Trying to pass data between viewControllers
问题描述
我在 NavigationController 中有 4 个 viewController 的序列，每个都从用户那里获取一些存储在 NSMutableDictionary 中的 textFields 输入.
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.
每个 VC 的集合本身在它继续之前作为 nextVC 的代表，它还传递 NSMutDict.
Each of the VC's set's itself up as the delegate of the nextVC before it segues, it also passes the NSMutDict along.
这很好用.
我不明白的是:
假设我已经填写了 VC1 中的 5 个 textField.然后我将自己设置为 VC2 的代表，将带有输入数据的字典传递给 VC2，然后转至 VC2.在 VC2 中，我填写了另外 4 个文本字段并将它们添加到字典中.如果我决定需要更改 VC1 中的某些内容，我会点击后退按钮并修改数据.但是当我再次前进时，我丢失了我在 VC2 上输入的内容.
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.
如何将带有添加信息的字典传回 VC1，以便当它再次传递给 VC2 时，它会包含所有内容?
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?
委托(VC1)有一个方法可以用VC2中的字典更新它的字典.
The delegate (VC1) has a method to update its dictionary with the dictionary in VC2.
我还在 VC2 中自定义了 backBarButtonItem，方法是在 VC1 的 prepareForSegue: 方法中设置它.
I have also customised the backBarButtonItem in VC2 by setting it in the prepareForSegue: method in VC1.
我想我正在接近但是...
I think I'm getting close but...
我只能通过在 VC2 中设置 leftBarButtonItem 并使用它而不是默认的后退按钮来使目标操作起作用.
I can only get the target actions to work by setting a leftBarButtonItem in VC2 and using that instead of the default back button.
在 VC1 (prepareForSegue:) 中设置后退按钮似乎不允许设置任何目标或操作.
Setting the back button in VC1 (prepareForSegue:) doesn't seem to allow any target or action to be set.
我知道我无法在 VC2 中设置后退按钮，那我该怎么办?我可以使用委托从 VC2 设置后退按钮的目标和动作吗?
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?
我认为这可能与 UINavigationBarDelegate 有关，但我不知道该把什么放在哪里.我尝试在 VC2 中设置它，但它没有做任何事情.
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.
相关代码如下:
协议:
#import <Foundation/Foundation.h>
@protocol IAXAddNewUserDelegate <NSObject>
@required
- (void)updateNewUserDataWithData: (NSMutableDictionary *)newData;
@end
来自 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
来自 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");
}
来自 VC2.m
-(void)passDataBack:(id)sender
{
NSLog(@"Sending Data Back to VC1");
[self.delegate updateNewUserDataWithData:self.userData];
[self.navigationController popViewControllerAnimated:YES];
}
推荐答案
如果您要更新所有其他词典中的所有词典，请尝试使用单例.您可以在此处查看示例:https://stackoverflow.com/a/9690731/542400
If you're updating all the dictionaries from all the other dictionaries, try using a singleton. You can see an example here: https://stackoverflow.com/a/9690731/542400
另外，这里有一些代码:
Also, here's some code:
MainDictionary.h
MainDictionary.h
@interface MainDictionary : NSObject{
NSMutableDictionary *dictionary;
}
+(MainDictionary *)sharedDictionary;
-(NSString *)getStringForKey:(NSString *)string;
-(void)setString:(NSString *)string forKey:(NSString *)key;
@end
MainDictionary.m
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
现在#import MainDictionary.h，以及任何时候您想访问或设置该字典中的值(在本例中，当您的文本字段结束编辑时)，只需执行以下操作:
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"];
}
}
或:
-(void)viewWillAppear{
textField1.text = [[MainDictionary sharedDictionary] getStringForKey:@"textField1"];
[super viewWillAppear:YES];
}
在每个 VC 中实现这一点，你就可以开始了.
Implement this in each VC, and you're good to go.
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