多个segues不在它们之间传递Object数据

Question

我已经开始了一个项目，该项目最初是在Appcoda关于使用视图控制器在场景之间传递数据的教程之后完成的（在此处查找：http://www.appcoda.com/storyboards-ios-tutorial-pass-data-between-view-controller-with-segue/）

基本上它需要来自第一个场景的表数据，而segue连接到另一个显示配方图像，准备时间和成分的控制器。但是我想更进一步，添加另一个视图控制器，它将显示如何准备配方的说明。所以到目前为止的运行是：

初始视图控制器（表格数据） - ＆gt; recipeDetailViewController - ＆gt; instructionsViewContoller

所以真的只有三个视图控制器，但都共享相同的数据。我想在视图控制器之间共享的数据是配方数据，格式为：

Recipe *recipe1 = [Recipe new];
recipe1.name = @"Egg Benedict";
recipe1.prepTime = @"30 min";
recipe1.imageFile = @"egg_benedictl.jpg";
recipe1.ingredients = [NSArray arrayWithObjects:@"2 fresh English muffins", @"4 eggs",    @"4 rashers of back bacon", @"2 egg yolks", @"1 tbsp of lemon juice", @"125 g of butter", @"salt and pepper", nil];
recipe1.instructions = @"This is recipe one's instruction set";

当然还有以下相关代码：

self.title = recipe.name;
self.prepTimeLabel.text = recipe.prepTime;
self.recipePhoto.image = [UIImage imageNamed:recipe.imageFile];

NSMutableString *ingredientText = [NSMutableString string];
for (NSString* ingredient in recipe.ingredients) {
    [ingredientText appendFormat:@"%@\n", ingredient];
}
self.ingredientTextView.text = ingredientText;

self.instructionTextView.text = recipe.instructions;

recipeLabel.text = recipeName;

然而，当我尝试将配方的指令传递给我的第三个视图控制器时获得混合结果。无论是什么也没有通过，拉丁文本字段占位符都会被传递，或者只有第一个食谱的recipe.instruction被传递给所有食谱，无论选择什么。我已经在这一个星期了一段时间，并认为是时候寻求希望了。

如果有人对如何在多个段之间传递我的食谱数据有任何建议，我将不胜感激。我从顶部文件开始粘贴下面的所有代码：

//
//  minuteMealsViewController.h
//  minuteMeals
//
//  Created by KMO on 8/18/12.
//  Copyright (c) 2012 KAM Digital. All rights reserved.
//

#import <UIKit/UIKit.h>
#import "Recipe.h"

@interface minuteMealsViewController : UIViewController <UITableViewDelegate, UITableViewDataSource>

@property (nonatomic, strong) IBOutlet UITableView *tableView;
//@property (nonatomic, weak) IBOutlet UIImageView *thumbnailImageView;



@end

---

//
//  minuteMealsViewController.m
//  minuteMeals
//
//  Created by KMO on 8/18/12.
//  Copyright (c) 2012 KAM Digital. All rights reserved.
//

#import "minuteMealsViewController.h"
#import "minuteMealsDetailViewController.h"
#import "Recipe.h"

@interface minuteMealsViewController ()

@end

@implementation minuteMealsViewController {
    NSArray *recipes;
    NSArray *thumbnails;
    NSArray *recipeTitle;
}
@synthesize tableView;


//@synthesize thumbnailImageView;

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Initialize table data

    Recipe *recipe1 = [Recipe new];
    recipe1.name = @"Egg Benedict";
    recipe1.prepTime = @"30 min";
    recipe1.imageFile = @"egg_benedictl.jpg";
    recipe1.ingredients = [NSArray arrayWithObjects:@"2 fresh English muffins", @"4 eggs", @"4 rashers of back bacon", @"2 egg yolks", @"1 tbsp of lemon juice", @"125 g of butter", @"salt and pepper", nil];
    recipe1.instructions = @"This is recipe one's instruction set";

    Recipe *recipe2 = [Recipe new];
    recipe2.name = @"Mushroom Risotto";
    recipe2.prepTime = @"30 min";
    recipe2.imageFile = @"mushroom_risottol.jpg";
    recipe2.ingredients = [NSArray arrayWithObjects:@"1 tbsp dried porcini mushrooms", @"2 tbsp olive oil", @"1 onion, chopped", @"2 garlic cloves", @"350g/12oz arborio rice", @"1.2 litres/2 pints hot vegetable stock", @"salt and pepper", @"25g/1oz butter", nil];
    recipe2.instructions = @"This is recipe two's instruction set";

    Recipe *recipe3 = [Recipe new];
    recipe3.name = @"Full Breakfast";
    recipe3.prepTime = @"20 min";
    recipe3.imageFile = @"full_breakfastl.jpg";
    recipe3.ingredients = [NSArray arrayWithObjects:@"2 sausages", @"100 grams of mushrooms", @"2 rashers of bacon", @"2 eggs", @"150 grams of baked beans", @"Vegetable oil", nil];

    Recipe *recipe4 = [Recipe new];
    recipe4.name = @"Hamburger";
    recipe4.prepTime = @"30 min";
    recipe4.imageFile = @"hamburgerl.jpg";
    recipe4.ingredients = [NSArray arrayWithObjects:@"400g of ground beef", @"1/4 onion (minced)", @"1 tbsp butter", @"hamburger bun", @"1 teaspoon dry mustard", @"Salt and pepper", nil];

    Recipe *recipe5 = [Recipe new];
    recipe5.name = @"Ham and Egg Sandwich";
    recipe5.prepTime = @"10 min";
    recipe5.imageFile = @"ham_and_egg_sandwichl.jpg";
    recipe5.ingredients = [NSArray arrayWithObjects:@"1 unsliced loaf (1 pound) French bread", @"4 tablespoons butter", @"2 tablespoons mayonnaise", @"8 thin slices deli ham", @"1 large tomato, sliced", @"1 small onion", @"8 eggs", @"8 slices cheddar cheese", nil];

    Recipe *recipe6 = [Recipe new];
    recipe6.name = @"Creme Brelee";
    recipe6.prepTime = @"1 hour";
    recipe6.imageFile = @"creme_breleel.jpg";
    recipe6.ingredients = [NSArray arrayWithObjects:@"1 quart heavy cream", @"1 vanilla bean, split and scraped", @"1 cup vanilla sugar", @"6 large egg yolks", @"2 quarts hot water", nil];

    Recipe *recipe7 = [Recipe new];
    recipe7.name = @"White Chocolate Donut";
    recipe7.prepTime = @"45 min";
    recipe7.imageFile = @"white_chocolate_donutl.jpg";
    recipe7.ingredients = [NSArray arrayWithObjects:@"3 1/4 cups flour", @"2 teaspoons baking powder", @"1/4 teaspoon salt", @"2 beaten eggs", @"2/3 cup sugar", @"2 ounces melted white chocolate", @"1/2 cup milk", nil];

    Recipe *recipe8 = [Recipe new];
    recipe8.name = @"White Chocolate Mocha";
    recipe8.prepTime = @"5 min";
    recipe8.imageFile = @"starbucks_coffeel.jpg";
    recipe8.ingredients = [NSArray arrayWithObjects:@"2/3 cup whole milk", @"6 tablespoons white chocolate chips", @"coffee", @"whipped cream", nil];

    Recipe *recipe9 = [Recipe new];
    recipe9.name = @"Vegetable Curry";
    recipe9.prepTime = @"30 min";
    recipe9.imageFile = @"vegetable_curryl.jpg";
    recipe9.ingredients = [NSArray arrayWithObjects:@"1 tablespoon olive oil", @"1 onion, chopped", @"2 cloves garlic", @"2 1/2 tablespoons curry powder", @"2 quarts hot water", nil];

    Recipe *recipe10 = [Recipe new];
    recipe10.name = @"Instant Noodle with Egg";
    recipe10.prepTime = @"8 min";
    recipe10.imageFile = @"instant_noodle_with_eggl.jpg";
    recipe10.ingredients = [NSArray arrayWithObjects:@"1 pack of Instant Noodle", @"2 eggs", nil];

    Recipe *recipe11 = [Recipe new];
    recipe11.name = @"Noodle with BBQ Pork";
    recipe11.prepTime = @"20 min";
    recipe11.imageFile = @"noodle_with_bbq_porkl.jpg";
    recipe11.ingredients = [NSArray arrayWithObjects:@"1 pack of Instant Noodle", @"BBQ pork", @"Salt and Pepper", nil];

    Recipe *recipe12 = [Recipe new];
    recipe12.name = @"Japanese Noodle with Pork";
    recipe12.prepTime = @"20 min";
    recipe12.imageFile = @"japanese_noodle_with_porkl.jpg";
    recipe12.ingredients = [NSArray arrayWithObjects:@"1 pack of Japanese Noodle", @"2 green onions", @"2 garlic cloves, minced", @"4 boneless pork loin chops", nil];

    Recipe *recipe13 = [Recipe new];
    recipe13.name = @"Green Tea";
    recipe13.prepTime = @"5 min";
    recipe13.imageFile = @"green_teal.jpg";
    recipe13.ingredients = [NSArray arrayWithObjects:@"Green tea", nil];

    Recipe *recipe14 = [Recipe new];
    recipe14.name = @"Thai Shrimp Cake";
    recipe14.prepTime = @"1.5 hours";
    recipe14.imageFile = @"thai_shrimp_cakel.jpg";
    recipe14.ingredients = [NSArray arrayWithObjects:@"8 oz (250g) peeled and deveined raw shrimp", @"2 tablespoons red curry paste", @"1 large egg", @"2 teaspoon fish sauce", @"1 tablespoon sugar", @"2 tablespoons coconut milk", @"2 tablespoons roughly chopped Thai basil leaves", nil];

    Recipe *recipe15 = [Recipe new];
    recipe15.name = @"Angry Birds Cake";
    recipe15.prepTime = @"4 hours";
    recipe15.imageFile = @"angry_birds_cakel.jpg";
    recipe15.ingredients = [NSArray arrayWithObjects:@"12 tablespoons (1 1/2 sticks) unsalted butter", @"2 1/2 cups all-purpose flour", @"1 tablespoon baking powder", @"1 teaspoon salt", @"1 3/4 cups sugar", @"2 large eggs, plus 3 large egg yolks", @"1 cup of milk", nil];

    Recipe *recipe16 = [Recipe new];
    recipe16.name = @"Ham and Cheese Panini";
    recipe16.prepTime = @"10 min";
    recipe16.imageFile = @"ham_and_cheese_paninil.jpg";
    recipe16.ingredients = [NSArray arrayWithObjects:@"2 tablespoons unsalted butter", @"4 cups thinly sliced shallots", @"2 teaspoons fresh thyme", @"1/4 cup grainy Dijon mustard", @"8 slices rustic white bread", @"8 slices Gruyere cheese", @"8 ounces sliced cooked ham", nil];

    recipeTitle = [NSArray arrayWithObjects:@"Egg Benedict", @"Mushroom Risotto", @"Full Breakfast", @"Hamburger", @"Ham and Egg Sandwich", @"Creme Brelee", @"White Chocolate Donut", @"Starbucks Coffee", @"Vegetable Curry", @"Instant Noodle with Egg", @"Noodle with BBQ Pork", @"Japanese Noodle with Pork", @"Green Tea", @"Thai Shrimp Cake", @"Angry Birds Cake", @"Ham and Cheese Panini", nil];


    recipes = [NSArray arrayWithObjects:recipe1, recipe2, recipe3, recipe4, recipe5, recipe6, recipe7, recipe8, recipe9, recipe10, recipe11, recipe12, recipe13, recipe14, recipe15, recipe16, nil];



    thumbnails = [NSArray arrayWithObjects:@"egg_benedict.jpg", @"mushroom_risotto.jpg", @"full_breakfast.jpg", @"hamburger.jpg", @"ham_and_egg_sandwich.jpg", @"creme_brelee.jpg", @"white_chocolate_donut.jpg", @"starbucks_coffee.jpg", @"vegetable_curry.jpg", @"instant_noodle_with_egg.jpg", @"noodle_with_bbq_pork.jpg", @"japanese_noodle_with_pork.jpg", @"green_tea.jpg", @"thai_shrimp_cake.jpg", @"angry_birds_cake.jpg", @"ham_and_cheese_panini.jpg", nil];
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [recipeTitle count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *simpleTableIdentifier = @"RecipeCell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];

    if (cell == nil)
    {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:simpleTableIdentifier];
    }
    cell.textLabel.text = [recipeTitle objectAtIndex:indexPath.row];
    cell.imageView.image = [UIImage imageNamed:[thumbnails objectAtIndex:indexPath.row]];

    return cell;
}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"showRecipeDetail"]) {
        NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];

        minuteMealsDetailViewController *destViewController = segue.destinationViewController;

        destViewController.recipe = [recipes objectAtIndex:indexPath.row];
    }
    NSLog(@"showRecipeDetial Segue is being passed");
}

- (void)viewDidUnload
{
    [self setTableView:nil];
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
        return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
    } else {
        return YES;
    }
}

@end

---

//
//  minuteMealsDetailViewController.h
//  minuteMeals
//
//  Created by KMO on 8/18/12.
//  Copyright (c) 2012 KAM Digital. All rights reserved.
//

#import <UIKit/UIKit.h>
#import "Recipe.h"

@interface minuteMealsDetailViewController : UIViewController

@property (strong, nonatomic) IBOutlet UIImageView *recipePhoto;

@property (strong, nonatomic) IBOutlet UILabel *prepTimeLabel;

@property (strong, nonatomic) IBOutlet UITextView *ingredientTextView;

@property (nonatomic, strong) IBOutlet UILabel *recipeLabel;

@property (nonatomic, strong) NSString *recipeName;

@property (nonatomic, strong) Recipe *recipe;

@property (strong, nonatomic) IBOutlet UITextView *instructionTextView;



@end

---

//
//  minuteMealsDetailViewController.m
//  minuteMeals
//
//  Created by KMO on 8/18/12.
//  Copyright (c) 2012 KAM Digital. All rights reserved.
//

#import "minuteMealsViewController.h"
#import "minuteMealsDetailViewController.h"
#import "Recipe.h"

@interface minuteMealsDetailViewController ()

@end

@implementation minuteMealsDetailViewController

@synthesize recipePhoto;
@synthesize prepTimeLabel;
@synthesize ingredientTextView;
@synthesize recipeLabel;
@synthesize recipeName;
@synthesize recipe;
@synthesize instructionTextView;



- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];


    self.title = recipe.name;
    self.prepTimeLabel.text = recipe.prepTime;
    self.recipePhoto.image = [UIImage imageNamed:recipe.imageFile];

    NSMutableString *ingredientText = [NSMutableString string];
    for (NSString* ingredient in recipe.ingredients) {
        [ingredientText appendFormat:@"%@\n", ingredient];
    }
    self.ingredientTextView.text = ingredientText;

    self.instructionTextView.text = recipe.instructions;

    recipeLabel.text = recipeName;
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"showInstructions"]) {

        minuteMealsDetailViewController *destViewController = segue.destinationViewController;

        destViewController.instructionTextView.text = [recipe instructions];

    }
    NSLog(@"showInstructions Seque is being passed");
}


/*- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"showRecipeDetail"]) {
        NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];

        minuteMealsDetailViewController *destViewController = segue.destinationViewController;

        destViewController.recipe = [recipes objectAtIndex:indexPath.row];
    }
    NSLog(@"showRecipeDetial Segue is being passed");
}*/

- (void)viewDidUnload
{
    [self setRecipePhoto:nil];
    [self setPrepTimeLabel:nil];
    [self setIngredientTextView:nil];
    [self setInstructionTextView:nil];
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}


- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

@end

---

//
//  Recipe.h
//  minuteMeals
//
//  Created by KMO on 8/19/12.
//  Copyright (c) 2012 KAM Digital. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Recipe : NSObject

@property (nonatomic, strong) NSString *name; // name of recipe
@property (nonatomic, strong) NSString *prepTime; // preparation time
@property (nonatomic, strong) NSString *imageFile; // image filename of recipe
@property (nonatomic, strong) NSArray *ingredients; // ingredients
@property (nonatomic, strong) NSString *instructions; // instruction set

@end

---

//
//  Recipe.m
//  minuteMeals
//
//  Created by KMO on 8/19/12.
//  Copyright (c) 2012 KAM Digital. All rights reserved.
//

#import "Recipe.h"

@implementation Recipe

@synthesize name;
@synthesize prepTime;
@synthesize imageFile;
@synthesize ingredients;
@synthesize instructions;

@end

Answer 1

首先尝试将指令设置为自己的属性，然后在viewDidLoad

中设置标签

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"showInstructions"]) {

        minuteMealsDetailViewController *destViewController = segue.destinationViewController;

        destViewController.instructionText = [recipe instructions];

    }
    NSLog(@"showInstructions Seque is being passed");
}

instructionText是新属性。

并在viewDidLoad中为您的指令ViewController执行

instructionTextView.text = self.instructionText;

修改

您没有看到任何内容的原因是视图未在prepareForSegue中完全加载，并且视图的所有初始化都应该在viewDidLoad中。在可以安全地更改您的视图时调用该方法。

您现在对“recipeDetail”和“instructions”使用相同的viewcontroller 我建议为你提供一个单独的viewController类。

只需将您的指令作为该viewController中的属性传递。

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"showInstructions"]) {

        MinuteMealsInstructionsViewController *destViewController = segue.destinationViewController;

        destViewController.instructionText = [recipe instructions];

    }
    NSLog(@"showInstructions Seque is being passed");
}

其中MinuteMealsInstructionsViewController是带有instructions属性的新类。

您说要保留配方对象中包含的配方。这仍然是正确的，因为您只传递对象成员的引用。假设你改变了指令字符串，那么它也会在你的配方对象中改变，因为字符串只是一个引用。

旁注：您应该根据Objective-c风格指南使用大写字母开始您的班级名称。

如果你真的想在同一个viewController中做到这一点，你可以简单地传递整个配方对象destViewController.recipe = recipe;和viewDidLoad：

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.instructionTextLabel = recipe.instructions;
}