将数据从 Google Places API 发送到 tableview

Question

如何使用 Objective-C 将数据发送到 iOS 中的 tableview？我试图解决我的问题很长时间，但结果不正确。我的表格视图仍然是空的。我做错了什么？下面是我的实现文件。

import "PlacesViewController.h"

@implementation PlacesViewController
@synthesize places;

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Set this view controller object as the delegate and data source for the table view
    self.listTableView.delegate = self;
    self.listTableView.dataSource = self;
}

-(void)queryGooglePlaces
{
    //Build the url string to send to Google
    NSString *url = [NSString stringWithFormat:@"https://maps.googleapis.com/maps/api/place/nearbysearch/json?location=51.503186,-0.126446&radius=5000&types=food@|restaurant|bar&keyword=vegetarian&key=myOwnKEY"];
    url = [url stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

    NSLog(@"%@", url);

    //Formulate the string as a URL object.
    NSURL *googleRequestURL=[NSURL URLWithString:url];

    // Retrieve the results of the URL.
    dispatch_async(kBgQueue, ^{
        NSData* data = [NSData dataWithContentsOfURL: googleRequestURL];
        dispatch_sync(dispatch_get_main_queue(), ^{
            [self fetchedData:data];
        });
    });
}

-(void)fetchedData:(NSData *)responseData {
    //parse out the json data
    NSError* error;
    NSDictionary* json = [NSJSONSerialization
                          JSONObjectWithData:responseData

                          options:kNilOptions
                          error:&error];

    //The results from Google will be an array obtained from the NSDictionary object with the key "results".
    self.places = [json objectForKey:@"results"];

    //Write out the data to the console.
    NSLog(@"Google Data: %@", json);
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    // Return the number of sections.
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    // Return the number of rows in the section.
    return [self.places count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

    NSDictionary *tempDictionary= [self.places objectAtIndex:indexPath.row];

    cell.textLabel.text = [tempDictionary objectForKey:@"name"];
    return cell;
}

@end

Answer 1

每当你更新数据源时，你需要调用[self.tableView reloadData]

所以应该是这样的

-(void)fetchedData:(NSData *)responseData {
    //parse out the json data
    NSError* error;
    NSDictionary* json = [NSJSONSerialization
                          JSONObjectWithData:responseData

                          options:kNilOptions
                          error:&error];

    //The results from Google will be an array obtained from the NSDictionary object with the key "results".
    self.places = [json objectForKey:@"results"];

    // NOTE - ADDED RELOAD
    [self.tableView reloadData];

    //Write out the data to the console.
    NSLog(@"Google Data: %@", json);
}

有关reloadData 的更多信息，请参阅the answer

Answer 2

更新数据源后，您应该重新加载表格视图。

self.places = [json objectForKey:@"results"];
[self.tableView reloadData];