Add a placeholder in the computer list if none are found. Retry service discovery if it fails.

Limelight/Network/MDNSManager.m

@@ -9,10 +9,12 @@
 #import "MDNSManager.h"
 #import "Computer.h"
 
-@implementation MDNSManager : NSObject
-NSNetServiceBrowser* mDNSBrowser;
-NSMutableArray* domains;
-NSMutableArray* services;
+@implementation MDNSManager {
+    NSNetServiceBrowser* mDNSBrowser;
+    NSMutableArray* domains;
+    NSMutableArray* services;
+    BOOL scanActive;
+}
 
 static NSString* NV_SERVICE_TYPE = @"_nvstream._tcp";
 
@@ -32,11 +34,13 @@ static NSString* NV_SERVICE_TYPE = @"_nvstream._tcp";
 
 - (void) searchForHosts {
     NSLog(@"Starting mDNS discovery");
+    scanActive = TRUE;
     [mDNSBrowser searchForServicesOfType:NV_SERVICE_TYPE inDomain:@""];
 }
 
 - (void) stopSearching {
     NSLog(@"Stopping mDNS discovery");
+    scanActive = FALSE;
     [mDNSBrowser stop];
 }
 
@@ -47,7 +51,7 @@ static NSString* NV_SERVICE_TYPE = @"_nvstream._tcp";
             [hosts addObject:[[Computer alloc] initWithHost:service]];
         }
     }
-    return [[NSArray alloc] initWithArray:hosts];
+    return hosts;
 }
 
 - (void)netServiceDidResolveAddress:(NSNetService *)service {
@@ -74,6 +78,24 @@ static NSString* NV_SERVICE_TYPE = @"_nvstream._tcp";
 - (void)netServiceBrowser:(NSNetServiceBrowser *)aNetServiceBrowser didNotSearch:(NSDictionary *)errorDict {
     NSLog(@"Did not perform search");
     NSLog(@"%@", [errorDict description]);
+    
+    // Schedule a retry in 2 seconds
+    [NSTimer scheduledTimerWithTimeInterval:2.0
+                                     target:self
+                                   selector:@selector(retryTimerCallback:)
+                                   userInfo:nil
+                                    repeats:NO];
+}
+
+- (void)retryTimerCallback:(NSTimer *)timer {
+    // Check if we've been stopped since this was queued
+    if (!scanActive) {
+        return;
+    }
+    
+    NSLog(@"Retrying mDNS search");
+    [mDNSBrowser stop];
+    [mDNSBrowser searchForServicesOfType:NV_SERVICE_TYPE inDomain:@""];
 }
 
 @end

Limelight/Utility/Computer.h

@@ -15,5 +15,6 @@
 
 - (id) initWithHost:(NSNetService*)host;
 - (id) initWithIp:(NSString*)host;
+- (id) initPlaceholder;
 
 @end

Limelight/Utility/Computer.m

@@ -28,4 +28,13 @@
     return self;
 }
 
+- (id) initPlaceholder {
+    self = [super init];
+    
+    self.hostName = NULL;
+    self.displayName = @"No computers found";
+    
+    return self;
+}
+
 @end

Limelight/ViewControllers/MainFrameViewController.m

@@ -122,10 +122,19 @@ static StreamConfiguration* streamConfig;
     }
 }
 
+- (void)setSelectedHost:(NSInteger)selectedIndex
+{
+    _selectedHost = (Computer*)([self.hostPickerVals objectAtIndex:selectedIndex]);
+    if (_selectedHost.hostName == NULL) {
+        // This must be the placeholder computer
+        _selectedHost = NULL;
+    }
+}
+
 - (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
 {
     if (pickerView == self.HostPicker) {
-        _selectedHost = (Computer*)([self.hostPickerVals objectAtIndex:[self.HostPicker selectedRowInComponent:0]]);
+        [self setSelectedHost:[self.HostPicker selectedRowInComponent:0]];
     }
     
     //TODO: figure out how to save this info!!
@@ -154,10 +163,12 @@ static StreamConfiguration* streamConfig;
     [super viewDidLoad];
 
     self.streamConfigVals = [[NSArray alloc] initWithObjects:@"1280x720 (30Hz)", @"1280x720 (60Hz)", @"1920x1080 (30Hz)", @"1920x1080 (60Hz)",nil];
-    self.hostPickerVals = [[NSArray alloc] init];
     [self.StreamConfigs selectRow:1 inComponent:0 animated:NO];
     
     _opQueue = [[NSOperationQueue alloc] init];
+    
+    // Initialize the host picker list
+    [self updateHosts:[[NSArray alloc] init]];
 }
 
 - (void)viewDidAppear:(BOOL)animated
@@ -172,9 +183,16 @@ static StreamConfiguration* streamConfig;
 }
 
 - (void)updateHosts:(NSArray *)hosts {
-    self.hostPickerVals = hosts;
+    NSMutableArray *hostPickerValues = [[NSMutableArray alloc] initWithArray:hosts];
+    
+    if ([hostPickerValues count] == 0) {
+        [hostPickerValues addObject:[[Computer alloc] initPlaceholder]];
+    }
+    
+    self.hostPickerVals = hostPickerValues;
     [self.HostPicker reloadAllComponents];
-    _selectedHost = (Computer*)([self.hostPickerVals objectAtIndex:[self.HostPicker selectedRowInComponent:0]]);
+    
+    [self setSelectedHost:[self.HostPicker selectedRowInComponent:0]];
 }
 
 - (void)didReceiveMemoryWarning