ios - ViewController 没有正确地将 NSURL 数据发送到目标 ViewController

Question

当用户点击一个单元格时，我希望将 itemURL 设置为该单元格的“Item URL”属性。执行此操作后，它应该将 prepareForSegue 中的 itemURL 发送到 WebViewController，正如我尝试做的那样。但是，当我有 WebViewController NSLog itemURL 属性时，它显示为 null。我怎样才能确保值(value)被正确发送？

MatchCenterViewController.h:

#import <UIKit/UIKit.h>
#import <Parse/Parse.h>
#import "AsyncImageView.h"
#import "SearchViewController.h"
#import "WebViewController.h"



@interface MatchCenterViewController : UIViewController <UITableViewDataSource>

@property (nonatomic) IBOutlet NSString *itemSearch;

@property (nonatomic, strong) NSArray *imageURLs;
@property (strong, nonatomic) NSString *matchingCategoryCondition;
@property (strong, nonatomic) NSString *matchingCategoryLocation;
@property (strong, nonatomic) NSNumber *matchingCategoryMaxPrice;
@property (strong, nonatomic) NSNumber *matchingCategoryMinPrice;

@property (strong, nonatomic) NSArray *matchCenterArray;
@property (strong, nonatomic) NSString *searchTerm;

@property (strong, nonatomic) NSURL *itemURL;

@end

MatchCenterViewController.m:

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

@interface MatchCenterViewController () <UITableViewDataSource, UITableViewDelegate>
@property (nonatomic, strong) UITableView *matchCenter;
@end

@implementation MatchCenterViewController


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


- (void)viewDidLoad
{
    [super viewDidLoad];

    self.matchCenter = [[UITableView alloc] initWithFrame:self.view.bounds style:UITableViewCellStyleSubtitle];
    self.matchCenter.frame = CGRectMake(0,50,320,self.view.frame.size.height-100);
    _matchCenter.dataSource = self;
    _matchCenter.delegate = self;
    [self.view addSubview:self.matchCenter];

    _matchCenterArray = [[NSArray alloc] init];
}

- (void)viewDidAppear:(BOOL)animated
{
    self.matchCenterArray = [[NSArray alloc] init];

    [PFCloud callFunctionInBackground:@"MatchCenter"
                       withParameters:@{
                                        @"test": @"Hi",
                                        }
                                block:^(NSArray *result, NSError *error) {

                                    if (!error) {
                                        _matchCenterArray = result;
                                        [_matchCenter reloadData];

                                        NSLog(@"Result: '%@'", result);
                                    }
                                }];
}


- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return _matchCenterArray.count;
}

//the part where i setup sections and the deleting of said sections

- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section {
    return 21.0f;
}


- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
    UIView *headerView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 21)];
    headerView.backgroundColor = [UIColor lightGrayColor];

    _searchTerm = [[[[_matchCenterArray  objectAtIndex:section] objectForKey:@"Top 3"] objectAtIndex:3]objectForKey:@"Search Term"];

    UILabel *headerLabel = [[UILabel alloc] initWithFrame:CGRectMake(8, 0, 250, 21)];
    headerLabel.text = [NSString stringWithFormat:@"%@", _searchTerm];
    headerLabel.font = [UIFont boldSystemFontOfSize:[UIFont systemFontSize]];
    headerLabel.textColor = [UIColor whiteColor];
    headerLabel.backgroundColor = [UIColor lightGrayColor];
    [headerView addSubview:headerLabel];


    UIButton *deleteButton = [UIButton buttonWithType:UIButtonTypeCustom];
    deleteButton.tag = section;
    deleteButton.frame = CGRectMake(300, 2, 17, 17);
    [deleteButton setImage:[UIImage imageNamed:@"xbutton.png"] forState:UIControlStateNormal];
    [deleteButton addTarget:self action:@selector(deleteButtonPressed:) forControlEvents:UIControlEventTouchUpInside];
    [headerView addSubview:deleteButton];
    return headerView;

}



- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 3;
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Initialize cell
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (!cell) {
        // if no cell could be dequeued create a new one
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
    }

    // No cell seperators = clean design
    tableView.separatorColor = [UIColor clearColor];

    // title of the item
    cell.textLabel.text = _matchCenterArray[indexPath.section][@"Top 3"][indexPath.row][@"Title"];
    cell.textLabel.font = [UIFont boldSystemFontOfSize:14];

    // price of the item
    cell.detailTextLabel.text = [NSString stringWithFormat:@"$%@", _matchCenterArray[indexPath.section][@"Top 3"][indexPath.row][@"Price"]];
    cell.detailTextLabel.textColor = [UIColor colorWithRed:0/255.0f green:127/255.0f blue:31/255.0f alpha:1.0f];

    // image of the item
    NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:_matchCenterArray[indexPath.section][@"Top 3"][indexPath.row][@"Image URL"]]];
    [[cell imageView] setImage:[UIImage imageWithData:imageData]];

    return cell;

}


- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    return 65;
}


- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSURL *itemURL = _matchCenterArray[indexPath.section][@"Top 3"][indexPath.row][@"Item URL"];

//    NSLog(@"The url is: '%@'", itemURL);

    [self performSegueWithIdentifier:@"WebViewSegue" sender:self];
}


- (void)deleteButtonPressed:(id)sender
{
    // links button
    UIButton *deleteButton = (UIButton *)sender;

    // Define the sections title
    NSString *sectionName = _searchTerm = [[[[_matchCenterArray  objectAtIndex:deleteButton.tag] objectForKey:@"Top 3"] objectAtIndex:3]objectForKey:@"Search Term"];

    // Run delete function with respective section header as parameter
    [PFCloud callFunctionInBackground:@"deleteFromMatchCenter"
                       withParameters:
                      @{@"searchTerm": sectionName,}
                                block:^(NSDictionary *result, NSError *error) {
                                   if (!error) {
                                       [PFCloud callFunctionInBackground:@"MatchCenter"
                                                          withParameters:@{
                                                                           @"test": @"Hi",
                                                                           }
                                                                   block:^(NSArray *result, NSError *error) {

                                                                       if (!error) {
                                                                           _matchCenterArray = result;
                                                                           [_matchCenter reloadData];

                                                                           NSLog(@"Result: '%@'", result);
                                                                       }
                                                                   }];

                                   }
                                }];
}



- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}



 #pragma mark - Navigation

 - (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
 {


     WebViewController *controller = (WebViewController *) segue.destinationViewController;
     controller.itemURL = self.itemURL;


 }


@end

WebViewController.h:

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

@interface WebViewController : UIViewController <UIWebViewDelegate>

@property (strong, nonatomic) NSURL *itemURL;
@property (weak, nonatomic) IBOutlet UIWebView *myWebView;

@end

WebViewController.m:

#import "WebViewController.h"

@interface WebViewController ()

@end

@implementation WebViewController

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


- (void)viewDidLoad
{
    [super viewDidLoad];
    NSLog(@"The url is: '%@'", _itemURL);

//    _myWebView=[[UIWebView alloc] initWithFrame:CGRectMake(0, 0, 320, 460)];
//    _myWebView.delegate=self;
//    [self.view addSubview:_myWebView];

    self.myWebView.delegate = self;

    //////////
    NSURLRequest *request = [NSURLRequest requestWithURL:_itemURL];
    //4
    NSOperationQueue *queue = [[NSOperationQueue alloc] init];

    //5
    [NSURLConnection sendAsynchronousRequest:request queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *error)
     {
         if ([data length] > 0 && error == nil) [self.myWebView loadRequest:request];
         else if (error != nil) NSLog(@"Error: %@", error);
     }];

    [self.myWebView setScalesPageToFit:YES];
    //////





    //[self.myWebView loadRequest:request];
}
- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

/*
#pragma mark - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}
*/

@end

Answer 1

在你的 didSelectRowForIndexPath: 而不是

NSURL *itemURL = _matchCenterArray[indexPath.section][@"Top 3"][indexPath.row][@"Item URL"];

使用

self.itemURL = _matchCenterArray[indexPath.section][@"Top 3"][indexPath.row][@"Item URL"];