PickerViewController.m

/*
     File: PickerViewController.m
 Abstract: Displays a table of services that the user can pick.
  Version: 2.1
 
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 */

#import "PickerViewController.h"

@import QuartzCore;

@interface PickerViewController () <NSNetServiceBrowserDelegate>

@property (nonatomic, strong, readwrite) IBOutlet UILabel *     localServiceNameLabel;

@property (nonatomic, strong, readwrite) UIFont *               localServiceNameLabelFont;      // latched from localServiceNameLabel

@property (nonatomic, strong, readwrite) IBOutlet UIView *      connectView;
@property (nonatomic, strong, readwrite) IBOutlet UILabel *     connectLabel;

@property (nonatomic, copy,   readwrite) NSString *             connectLabelTemplate;           // latched from connectLabel

@property (nonatomic, strong, readonly ) NSMutableArray *       services;                       // of NSNetService, sorted by name
@property (nonatomic, strong, readwrite) NSNetServiceBrowser *  browser;

@end

@implementation PickerViewController

- (instancetype)init
{
    self = [super init];
    if (self != nil) {
        [self commonInit];
    }
    return self;
}

- (instancetype)initWithCoder:(NSCoder *)coder
{
    self = [super initWithCoder:coder];
    if (self) {
        [self commonInit];
    }
    return self;
}

- (void)commonInit
{
    self->_services = [[NSMutableArray alloc] init];
    // We observe localService so that we can react to the client changing it.
    [self addObserver:self forKeyPath:@"localService" options:0 context:&self->_localService];
}

- (void)dealloc
{
    [self removeObserver:self forKeyPath:@"localService" context:&self->_localService];
}

- (void)setupLocalServiceNameLabel
    // Called to set the local service name label in response to a change in the local service. 
    // It sets the label to either the actual name or "registering" if there's no local service.
{
    assert(self.localServiceNameLabel != nil);
    if (self.localService == nil) {
        self.localServiceNameLabel.font = [UIFont italicSystemFontOfSize:self.localServiceNameLabelFont.pointSize * 0.75f];
        self.localServiceNameLabel.text = @"registering…";
    } else {
        self.localServiceNameLabel.font = self.localServiceNameLabelFont;
        self.localServiceNameLabel.text = self.localService.name;
    }
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    if (context == &self->_localService) {
        assert([keyPath isEqual:@"localService"]);
        assert(object == self);
        
        // If there's a local service name label (that is, -viewDidLoad has been called), updated it.
        
        if (self.localServiceNameLabel != nil) {
            [self setupLocalServiceNameLabel];
        }
        
        // There's a chance that the browser saw our service before we heard about its successful 
        // registration, at which point we need to hide the service.  Doing that would be easy, 
        // but there are other edge cases to consider (for example, if the local service changes 
        // name, we would have to unhide the old name and hide the new name).  Rather than attempt 
        // to handle all of those edge cases we just stop and restart when the service name changes.
        
        if (self.browser != nil) {
            [self stop];
            [self start];
        }
    } else {
        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    }
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    assert(self.localServiceNameLabel != nil);
    assert(self.connectView  != nil);
    assert(self.connectLabel != nil);

    // Stash the original font for use by -setupLocalServiceNameLabel then call 
    // -setupLocalServiceNameLabel to apply the local service to our header.
    
    self.localServiceNameLabelFont = self.localServiceNameLabel.font;       
    [self setupLocalServiceNameLabel];

    // Set up the connect view and stash the label text for use as a template.

    self.connectView.layer.cornerRadius = 10.0f;
    self.connectView.layer.shadowColor = [UIColor blackColor].CGColor;
    self.connectView.layer.shadowOffset = CGSizeMake(3.0f, 3.0f);
    self.connectView.layer.shadowOpacity = 0.7f;
    
    self.connectLabelTemplate = self.connectLabel.text;
}

- (void)start
    // See comment in header.
{
    assert([self.services count] == 0);

    assert(self.browser == nil);
    
    self.browser = [[NSNetServiceBrowser alloc] init];
    self.browser.includesPeerToPeer = YES;
    [self.browser setDelegate:self];
    [self.browser searchForServicesOfType:self.type inDomain:@"local"];
}

- (void)stop
    // See comment in header.
{
    [self.browser stop];
    self.browser = nil;

    [self.services removeAllObjects];
    
    if (self.isViewLoaded) {
        [self.tableView reloadData];
    }
}

- (void)cancelConnect
    // See comment in header.
{
    [self hideConnectViewAndNotify:NO];
}

#pragma mark * Connection-in-progress UI management

- (void)showConnectViewForService:(NSNetService *)service
    // Shows a view that indicates we're connecting to the specified service.
{
    CGRect  selfViewBounds;

    // Show the connection UI.
    
    assert(self.connectView  != nil);               // views should be loaded
    assert(self.connectLabel != nil);               // ditto
    assert(self.connectView.superview == nil);      // connection view must not be in the view hierarchy
    
    self.connectLabel.text = [NSString stringWithFormat:self.connectLabelTemplate, [service name]];

    selfViewBounds = self.tableView.bounds;
    self.connectView.center = CGPointMake( CGRectGetMidX(selfViewBounds), CGRectGetMidY(selfViewBounds) );
    [self.tableView addSubview:self.connectView];
    
    // Disable user interactions on the table view to prevent the user doing 
    // stuff 'behind' our connection-in-progress UI.
     
    self.tableView.scrollEnabled = NO;
    self.tableView.allowsSelection = NO;

    // Tell the delegate.
    
    [self.delegate pickerViewController:self connectToService:service];
}

- (void)hideConnectViewAndNotify:(BOOL)notify
    // Hide the view we showed in -showConnectViewForService:
{
    if (self.connectView.superview != nil) {
        [self.connectView removeFromSuperview];

        self.tableView.scrollEnabled = YES;
        self.tableView.allowsSelection = YES;
    }
    if (notify) {
        [self.delegate pickerViewControllerDidCancelConnect:self];
    }
}

- (IBAction)connectCancelAction:(id)sender
    // Called when the user taps the Cancel button in the connection UI.  This hides the 
    // connection UI and tells the delegate about the cancellation.
{
    #pragma unused(sender)
    [self hideConnectViewAndNotify:YES];
}

#pragma mark * Table view callbacks

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    #pragma unused(tableView)
    #pragma unused(section)
    return (NSInteger) [self.services count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *	cell;
    NSNetService *      service;

    #pragma unused(tableView)
    
    service = [self.services objectAtIndex:(NSUInteger) indexPath.row];

    cell = [self.tableView dequeueReusableCellWithIdentifier:@"cell"];

    cell.textLabel.text = service.name;

    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSNetService *      service;

    #pragma unused(tableView)
    #pragma unused(indexPath)

    [self.tableView deselectRowAtIndexPath:indexPath animated:YES];

    // Find the service associated with the cell and start a connection to that.
    
    service = [self.services objectAtIndex:(NSUInteger) indexPath.row];
    [self showConnectViewForService:service];
}

#pragma mark * Browser view callbacks

- (void)sortAndReloadTable
{
    // Sort the services by name.

    [self.services sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {
        return [[obj1 name] localizedCaseInsensitiveCompare:[obj2 name]];
    }];
    
    // Reload if the view is loaded.
    
    if (self.isViewLoaded) {
        [self.tableView reloadData];
    }
}

- (void)netServiceBrowser:(NSNetServiceBrowser *)browser didRemoveService:(NSNetService *)service moreComing:(BOOL)moreComing
{
    assert(browser == self.browser);
    #pragma unused(browser)
    assert(service != nil);
    
    // Remove the service from our array (assume it's there, of course).
    
    if ( (self.localService == nil) || ! [self.localService isEqual:service] ) {
        [self.services removeObject:service];
    }
    
    // Only update the UI once we get the no-more-coming indication.
    
    if ( ! moreComing ) {
        [self sortAndReloadTable];
    }
}   

- (void)netServiceBrowser:(NSNetServiceBrowser *)browser didFindService:(NSNetService *)service moreComing:(BOOL)moreComing
{
    assert(browser == self.browser);
    #pragma unused(browser)
    assert(service != nil);
    
    // Add the service to our array (unless its our own service).

    if ( (self.localService == nil) || ! [self.localService isEqual:service] ) {
        [self.services addObject:service];
    }

    // Only update the UI once we get the no-more-coming indication.

    if ( ! moreComing ) {
        [self sortAndReloadTable];
    }
}

- (void)netServiceBrowser:(NSNetServiceBrowser *)browser didNotSearch:(NSDictionary *)errorDict
{
    assert(browser == self.browser);
    #pragma unused(browser)
    assert(errorDict != nil);
    #pragma unused(errorDict)
    assert(NO);         // The usual reason for us not searching is a programming error.
}

@end