[ios, osx] Centralized offline pack management

MGLOfflineStorage now maintains a centralized, strongly held, KVO-compliant collection of all extant offline packs. MGLOfflineStorage issues notifications for progress updates. Client code can now react to the successful addition of an offline pack either via the completion block or via a KVO insertion.

Fixes #4287.

1 files changed, 69 insertions, 41 deletions

diff --git a/platform/ios/app/MBXOfflinePacksTableViewController.m b/platform/ios/app/MBXOfflinePacksTableViewController.m
index fb9d5fb3ed..4f399d3d4f 100644
--- a/platform/ios/app/MBXOfflinePacksTableViewController.m
+++ b/platform/ios/app/MBXOfflinePacksTableViewController.m
@@ -28,12 +28,6 @@ static NSString * const MBXOfflinePacksTableViewActiveCellReuseIdentifier = @"Ac
 
 @end
 
-@interface MBXOfflinePacksTableViewController () <MGLOfflinePackDelegate>
-
-@property (nonatomic, strong) NS_MUTABLE_ARRAY_OF(MGLOfflinePack *) *offlinePacks;
-
-@end
-
 @implementation MBXOfflinePacksTableViewController {
     NSUInteger _untitledRegionCount;
 }
@@ -41,25 +35,48 @@ static NSString * const MBXOfflinePacksTableViewActiveCellReuseIdentifier = @"Ac
 - (void)viewDidLoad {
     [super viewDidLoad];
     
-    __weak MBXOfflinePacksTableViewController *weakSelf = self;
-    [[MGLOfflineStorage sharedOfflineStorage] getPacksWithCompletionHandler:^(NS_ARRAY_OF(MGLOfflinePack *) *packs, NSError *error) {
-        MBXOfflinePacksTableViewController *strongSelf = weakSelf;
-        strongSelf.offlinePacks = packs.mutableCopy;
-        [strongSelf.tableView reloadData];
-        
-        for (MGLOfflinePack *pack in strongSelf.offlinePacks) {
-            pack.delegate = strongSelf;
-            [pack requestProgress];
-        }
-        
-        if (error) {
-            UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Can’t Find Offline Packs" message:@"Mapbox GL was unable to find the existing offline packs." preferredStyle:UIAlertControllerStyleAlert];
-            [alertController addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:nil]];
-            [self presentViewController:alertController animated:YES completion:^{
-                [strongSelf dismissViewControllerAnimated:YES completion:nil];
+    [[MGLOfflineStorage sharedOfflineStorage] addObserver:self forKeyPath:@"packs" options:NSKeyValueObservingOptionInitial context:NULL];
+    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(offlinePackProgressDidChange:) name:MGLOfflinePackProgressChangedNotification object:nil];
+    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(offlinePackDidReceiveError:) name:MGLOfflinePackErrorNotification object:nil];
+    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(offlinePackDidReceiveMaximumAllowedMapboxTiles:) name:MGLOfflinePackMaximumMapboxTilesReachedNotification object:nil];
+}
+
+- (void)dealloc {
+    [[MGLOfflineStorage sharedOfflineStorage] removeObserver:self forKeyPath:@"packs"];
+    [[NSNotificationCenter defaultCenter] removeObserver:self];
+}
+
+- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NS_DICTIONARY_OF(NSString *, id) *)change context:(void *)context {
+    if ([keyPath isEqualToString:@"packs"]) {
+        NSKeyValueChange changeKind = [change[NSKeyValueChangeKindKey] unsignedIntegerValue];
+        NSIndexSet *indices = change[NSKeyValueChangeIndexesKey];
+        NSMutableArray *indexPaths;
+        if (indices) {
+            indexPaths = [NSMutableArray arrayWithCapacity:indices.count];
+            [indices enumerateIndexesUsingBlock:^(NSUInteger idx, BOOL * _Nonnull stop) {
+                [indexPaths addObject:[NSIndexPath indexPathForRow:idx inSection:0]];
             }];
         }
-    }];
+        switch (changeKind) {
+            case NSKeyValueChangeInsertion:
+                [self.tableView insertRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationAutomatic];
+                break;
+                
+            case NSKeyValueChangeRemoval:
+                [self.tableView deleteRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationAutomatic];
+                break;
+                
+            case NSKeyValueChangeReplacement:
+                [self.tableView reloadRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationAutomatic];
+                break;
+                
+            default:
+                [self.tableView reloadData];
+                break;
+        }
+    } else {
+        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
+    }
 }
 
 - (IBAction)addCurrentRegion:(id)sender {
@@ -89,13 +106,6 @@ static NSString * const MBXOfflinePacksTableViewActiveCellReuseIdentifier = @"Ac
                 UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Can’t Add Offline Pack" message:message preferredStyle:UIAlertControllerStyleAlert];
                 [alertController addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:nil]];
                 [self presentViewController:alertController animated:YES completion:nil];
-            } else {
-                pack.delegate = strongSelf;
-                [pack resume];
-                
-                NSIndexPath *indexPath = [NSIndexPath indexPathForRow:strongSelf.offlinePacks.count inSection:0];
-                [strongSelf.offlinePacks addObject:pack];
-                [strongSelf.tableView insertRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
             }
         }];
     }];
@@ -110,11 +120,11 @@ static NSString * const MBXOfflinePacksTableViewActiveCellReuseIdentifier = @"Ac
 #pragma mark - Table view data source
 
 - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
-    return self.offlinePacks.count;
+    return [MGLOfflineStorage sharedOfflineStorage].packs.count;
 }
 
 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
-    MGLOfflinePack *pack = self.offlinePacks[indexPath.row];
+    MGLOfflinePack *pack = [MGLOfflineStorage sharedOfflineStorage].packs[indexPath.row];
     
     NSString *reuseIdentifier = pack.state == MGLOfflinePackStateActive ? MBXOfflinePacksTableViewActiveCellReuseIdentifier : MBXOfflinePacksTableViewInactiveCellReuseIdentifier;
     UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:reuseIdentifier forIndexPath:indexPath];
@@ -165,9 +175,7 @@ static NSString * const MBXOfflinePacksTableViewActiveCellReuseIdentifier = @"Ac
 
 - (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
     if (editingStyle == UITableViewCellEditingStyleDelete) {
-        MGLOfflinePack *pack = self.offlinePacks[indexPath.row];
-        [self.offlinePacks removeObjectAtIndex:indexPath.row];
-        [self.tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
+        MGLOfflinePack *pack = [MGLOfflineStorage sharedOfflineStorage].packs[indexPath.row];
         [[MGLOfflineStorage sharedOfflineStorage] removePack:pack withCompletionHandler:nil];
     }
 }
@@ -177,7 +185,7 @@ static NSString * const MBXOfflinePacksTableViewActiveCellReuseIdentifier = @"Ac
 - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
     [tableView deselectRowAtIndexPath:indexPath animated:YES];
     
-    MGLOfflinePack *pack = self.offlinePacks[indexPath.row];
+    MGLOfflinePack *pack = [MGLOfflineStorage sharedOfflineStorage].packs[indexPath.row];
     switch (pack.state) {
         case MGLOfflinePackStateUnknown:
             break;
@@ -207,8 +215,11 @@ static NSString * const MBXOfflinePacksTableViewActiveCellReuseIdentifier = @"Ac
 
 #pragma mark - Offline pack delegate
 
-- (void)offlinePack:(MGLOfflinePack *)pack progressDidChange:(MGLOfflinePackProgress)progress {
-    NSUInteger index = [self.offlinePacks indexOfObject:pack];
+- (void)offlinePackProgressDidChange:(NSNotification *)notification {
+    MGLOfflinePack *pack = notification.object;
+    NSAssert([pack isKindOfClass:[MGLOfflinePack class]], @"MGLOfflineStorage notification has a non-pack object.");
+    
+    NSUInteger index = [[MGLOfflineStorage sharedOfflineStorage].packs indexOfObject:pack];
     if (index == NSNotFound) {
         return;
     }
@@ -217,11 +228,28 @@ static NSString * const MBXOfflinePacksTableViewActiveCellReuseIdentifier = @"Ac
     [self.tableView reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationNone];
 }
 
-- (void)offlinePack:(MGLOfflinePack *)pack didReceiveError:(NSError *)error {
-    NSLog(@"Offline pack “%@” received error: %@", pack.name, error.localizedFailureReason);
+- (void)offlinePackDidReceiveError:(NSNotification *)notification {
+    MGLOfflinePack *pack = notification.object;
+    NSAssert([pack isKindOfClass:[MGLOfflinePack class]], @"MGLOfflineStorage notification has a non-pack object.");
+    
+    NSError *error = notification.userInfo[MGLOfflinePackErrorUserInfoKey];
+    NSAssert([error isKindOfClass:[NSError class]], @"MGLOfflineStorage notification has a non-error error.");
+    
+    NSString *message = [NSString stringWithFormat:@"iosapp encountered an error while downloading the offline pack “%@”: %@", pack.name, error.localizedFailureReason];
+    if (error.code == MGLErrorCodeConnectionFailed) {
+        NSLog(@"%@", message);
+    } else {
+        UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Error Downloading Offline Pack" message:message preferredStyle:UIAlertControllerStyleAlert];
+        [alertController addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:nil]];
+        [self presentViewController:alertController animated:YES completion:nil];
+    }
 }
 
-- (void)offlinePack:(MGLOfflinePack *)pack didReceiveMaximumAllowedMapboxTiles:(uint64_t)maximumCount {
+- (void)offlinePackDidReceiveMaximumAllowedMapboxTiles:(NSNotification *)notification {
+    MGLOfflinePack *pack = notification.object;
+    NSAssert([pack isKindOfClass:[MGLOfflinePack class]], @"MGLOfflineStorage notification has a non-pack object.");
+    
+    uint64_t maximumCount = [notification.userInfo[MGLOfflinePackMaximumCountUserInfoKey] unsignedLongLongValue];
     NSLog(@"Offline pack “%@” reached limit of %llu tiles.", pack.name, maximumCount);
 }