按下UIButton时更改JSON数据链接

Question

I have an iPhone app were I parse JSON to a Table View and display the data in a custom cell. I have three different JSON files containing the same structure but with different data. I also have three different UIButtons displaying as a tab bar on the same page, like this:

I have two different images for the buttons - one when it's selected and one when it's unselected.

My code for parsing the JSON file looks like this:

#import "DEMOSecondViewController.h"
#import "DEMONavigationController.h"
#import "PostsObject.h"
#import "AFNetworking.h"

@interface DEMOSecondViewController ()

@end

@implementation DEMOSecondViewController
@synthesize tableView = _tableView, activityIndicatorView = _activityIndicatorView, movies = _movies;

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.title = @"iCelebri.com";
    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Menu"
                                                                             style:UIBarButtonItemStylePlain
                                                                            target:(DEMONavigationController *)self.navigationController
                                                                            action:@selector(showMenu)];

    self.tableView.separatorColor = [UIColor clearColor];

    // Setting Up Activity Indicator View
    self.activityIndicatorView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
    self.activityIndicatorView.hidesWhenStopped = YES;
    self.activityIndicatorView.center = self.view.center;
    [self.view addSubview:self.activityIndicatorView];
    [self.activityIndicatorView startAnimating];
    self.tableView.separatorColor = [UIColor clearColor];

    // Initializing Data Source
    self.movies = [[NSArray alloc] init];

    NSURL *url = [[NSURL alloc] initWithString:@"http://my-site.com/jsonfile.php?name=Name"];
    NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url];

    AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
        self.movies = JSON;
        [self.activityIndicatorView stopAnimating];
        [self.tableView reloadData];

    } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
        NSLog(@"Request Failed with Error: %@, %@", error, error.userInfo);
    }];

    [operation start];
}

// Table View Data Source Methods
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    if (self.movies && self.movies.count) {
        return self.movies.count;
    } else {
        return 0;
    }
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    return 124;
}

- (void)tableView:(UITableView *)tableView
  willDisplayCell:(UITableViewCell *)cell
forRowAtIndexPath:(NSIndexPath *)indexPath
{
    [cell setBackgroundColor:[UIColor clearColor]];
}

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

    PostsObject *cell = (PostsObject *)[tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];
    if (cell == nil)
    {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"PostsObject" owner:self options:nil];
        cell = [nib objectAtIndex:0];
        cell.selectionStyle = UITableViewCellSelectionStyleNone;
        UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"background.png"]];

        self.tableView.backgroundView = imageView;
    }

    NSDictionary *movie = [self.movies objectAtIndex:indexPath.row];
    cell.title.text = [movie objectForKey:@"message"];
    cell.published.text = [movie objectForKey:@"published"];

    return cell;
}


@end

So when I click for example the Twitter button, I want the NSURL *url = [[NSURL alloc] initWithString:@"http://my-site.com/jsonfile.php?name=Name"]; to change the link to another. It's like a UISegmentControl but with UIButtons instead.

How is this possible?

Thanks.

Answer 1

First connect to a property the 3 UIButtons on the tabBar I called them for the example:

btnFaceBook 
btnTwitter
btnTwitter2

Set for the 3 UIButtons the URL for that tab in -viewDidLoad like this:

[btnFaceBook setTitle:@"http://URLFacebook.com" forState:UIControlStateDisabled];
[btnTwitter setTitle:@"http://URLTwitter.com" forState:UIControlStateDisabled];
[btnTwitter2 setTitle:@"http://URLTwitter2.com" forState:UIControlStateDisabled];

Set for the 3 UIButtons the images for Unpressed and pressed, You can do that from your nib file or like that programatically:

[btnFaceBook setBackgroundImage:[UIImage imageNamed:@"imageFacebookUnpressedUnSelected.png"] forState:UIControlStateNormal];
[btnFaceBook setBackgroundImage:[UIImage imageNamed:@"imageFacebookPressedSelected.png"] forState:UIControlStateSelected];

[btnTwitter setBackgroundImage:[UIImage imageNamed:@"imageTwitterUnpressedUnSelected.png"] forState:UIControlStateNormal];
[btnTwitter setBackgroundImage:[UIImage imageNamed:@"imageTwitterPressedSelected.png"] forState:UIControlStateSelected];

[btnTwitter2 setBackgroundImage:[UIImage imageNamed:@"imageTwitter2UnpressedUnSelected.png"] forState:UIControlStateNormal];
[btnTwitter2 setBackgroundImage:[UIImage imageNamed:@"imageTwitter2PressedSelected.png"] forState:UIControlStateSelected];

Then connect all 3 UIButton's TouchUpInside action to this method:

- (IBAction)btnFromTabBarClicked:(UIButton *)sender
{
    //Unselect all 3 buttons
    btnFaceBook.selected = btnTwitter.selected = btnTwitter2.selected = NO;

    //Select the button that was clicked        
    sender.selected = YES;

    //Set the string of an NSMutableString property called strURLToLoad with the URL
    //The URL is pre stored in the text of the UIButton in the Disabled text.
    [strURLToLoad setString:[sender titleForState:UIControlStateDisabled]];

    //Load the URL
    [self loadJSONFromCurrentURL];
}

Answer 2

You can simply create a property for your NSURL so you can access it from all your class methods. Modify your code like this:

@interface DEMOSecondViewController ()
@property (strong) NSURL *url;
@end

Then in your viewDidLoad:

url = [[NSURL alloc] initWithString:@"http://my-site.com/jsonfile.php?name=Name"];

Then create an action for your buttons:

// Facebook button example. Do the same for the other 2 buttons
- (IBAction)facebookButton:(id)sender {
    url = [NSURL URLWithString:@"yourNewUrl"];
    // Here you need to call again your AFNewtorking code (maybe put it in a sperate method instead of the viewDidLoad)
}

I hope I well explained the answer :)