使用Parse.com將表格視圖控制器與詳細視圖控制器之間的數據傳遞

Question

我必須在表格視圖控制器和詳細視圖控制器之間傳遞數據，並且我使用Parse從後端加載數據，我使用local數據，這是源代碼：

表視圖控制器：

#import "RecipeBookViewController.h" 
#import "RecipeDetailViewController.h" 
#import "Recipe.h" 

@interface RecipeBookViewController() 

@end 

@implementation RecipeBookViewController { 
    NSArray *recipes; 
} 

@synthesize tableView = _tableView; 

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

    Recipe *recipe1 = [Recipe new]; 
    recipe1.name = @"Egg Benedict"; 
    recipe1.prepTime = @"30 min"; 
    recipe1.imageFile = @"egg_benedict.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]; 

    Recipe *recipe2 = [Recipe new]; 
    recipe2.name = @"Mushroom Risotto"; 
    recipe2.prepTime = @"30 min"; 
    recipe2.imageFile = @"mushroom_risotto.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]; 

    Recipe *recipe3 = [Recipe new]; 
    recipe3.name = @"Full Breakfast"; 
    recipe3.prepTime = @"20 min"; 
    recipe3.imageFile = @"full_breakfast.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 = @"hamburger.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_sandwich.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_brelee.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_donut.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_coffee.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_curry.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_egg.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_pork.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_pork.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_tea.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_cake.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_cake.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_panini.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]; 

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


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

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

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

    Recipe *recipe = [recipes objectAtIndex:indexPath.row]; 
    cell.textLabel.text = recipe.name; 

    return cell; 
} 


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

     // Hide bottom tab bar in the detail view 
    // destViewController.hidesBottomBarWhenPushed = YES; 
    } 
} 

詳細視圖控制器：

@interface RecipeDetailViewController() 

@end 

@implementation RecipeDetailViewController 

@synthesize recipePhoto; 
@synthesize prepTimeLabel; 
@synthesize ingredientTextView; 
@synthesize recipe; 


- (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; 

} 

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

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

@end 

我該如何使用Parse.com後端來做到這一點？

Answer 1

假設您在Parse後端中有一個Recipe類，您應該能夠簡單地替換您的初始化程序中用代理查詢創建配方的代碼，以替代它們來檢索它們。像下面這樣（注意我沒有確切檢查語法）：

PFQuery *recipeQuery = [PFQuery queryWithClassName:@"Recipe"]; 
[recipeQuery findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) { 
    if (!error) { 
     self.recipes = <Map parse objects to Recipe objects here>; 
    } 
}]; 

如果映射返回的解析對象到Recipe對象，你不應該需要從除了改變你的代碼的其餘部分中的任何，處理通過網絡加載內容的延遲（您可能希望向用戶顯示某種加載指示符）。

或者，您可以查看與Parse框架一起提供的PFQueryTableViewController，該框架可能會滿足您的所有需求。