Fixed race condition after setting access token

`Map` should be able to deal with having no access token or JSON even while it’s running. Most of `Map` accounts for this situation, but `reloadStyle()` incorrectly assumes that one or the other is set. This change corrects the assumption in `reloadStyle()`.

Also expose the access token and style name to clients as ordinary KVO-compliant properties. Actually, they’re not so ordinary because they’re inspectable!

Ref #1070, #1147

8 files changed, 66 insertions, 22 deletions

diff --git a/gyp/platform-ios.gypi b/gyp/platform-ios.gypi
index 9965db57ac..fc6771d83a 100644
--- a/gyp/platform-ios.gypi
+++ b/gyp/platform-ios.gypi
@@ -30,6 +30,8 @@
         '../include/mbgl/ios/MGLMetricsLocationManager.h',
         '../platform/ios/MGLMetricsLocationManager.m',
         '../include/mbgl/ios/MGLTypes.h',
+        '../platform/ios/NSString+MGLAdditions.h',
+        '../platform/ios/NSString+MGLAdditions.m',
         '../platform/ios/vendor/SMCalloutView/SMCalloutView.h',
         '../platform/ios/vendor/SMCalloutView/SMCalloutView.m',
       ],
@@ -50,6 +52,7 @@
           '-framework MobileCoreServices',
           '-framework QuartzCore',
           '-framework SystemConfiguration',
+          '-ObjC',
         ],
       },
 
diff --git a/include/mbgl/ios/MGLMapView.h b/include/mbgl/ios/MGLMapView.h
index 17741b1711..354e32cc5a 100644
--- a/include/mbgl/ios/MGLMapView.h
+++ b/include/mbgl/ios/MGLMapView.h
@@ -54,7 +54,7 @@
 
 /** Sets a Mapbox API access token for the map view. 
 *   @param accessToken A Mapbox API token. */
-- (void)setAccessToken:(NSString *)accessToken;
+@property (nonatomic) IBInspectable NSString *accessToken;
 
 #pragma mark - Managing Constraints
 
@@ -194,11 +194,11 @@
 
 /** Sets the map style to a named, bundled style.
 *   @param styleName The map style name to use. */
-- (void)useBundledStyleNamed:(NSString *)styleName;
+@property (nonatomic) IBInspectable NSString *styleName;
 
 /** Sets the map style URL to use.
 *   @param styleURL The map style URL to use. Can be either an HTTP/HTTPS URL or a Mapbox map ID style URL (`mapbox://<user.style>`). */
-- (void)setStyleURL:(NSURL *)styleURL;
+@property (nonatomic) NSURL *styleURL;
 
 #pragma mark - Annotating the Map
 
diff --git a/include/mbgl/map/map.hpp b/include/mbgl/map/map.hpp
index cdcfa27e42..764ff24ed8 100644
--- a/include/mbgl/map/map.hpp
+++ b/include/mbgl/map/map.hpp
@@ -96,6 +96,7 @@ public:
     Duration getDefaultTransitionDuration();
     void setStyleURL(const std::string& url);
     void setStyleJSON(const std::string& json, const std::string& base = "");
+    std::string getStyleURL() const;
     std::string getStyleJSON() const;
 
     // Transition
diff --git a/ios/app/MBXViewController.mm b/ios/app/MBXViewController.mm
index c9973bcb7d..1461439697 100644
--- a/ios/app/MBXViewController.mm
+++ b/ios/app/MBXViewController.mm
@@ -19,7 +19,7 @@ static NSArray *const kStyleNames = @[
     @"Hybrid",
 ];
 
-static NSString *const kStyleVersion = @"v7";
+static NSString *const kStyleVersion = @"7";
 
 @interface MBXViewController () <UIActionSheetDelegate, MGLMapViewDelegate>
 
@@ -246,10 +246,7 @@ mbgl::Settings_NSUserDefaults *settings = nullptr;
         styleName = [kStyleNames objectAtIndex:index];
     }
 
-    [self.mapView useBundledStyleNamed:
-        [[[styleName lowercaseString]
-        stringByAppendingString:@"-"]
-        stringByAppendingString:kStyleVersion]];
+    self.mapView.styleName = [NSString stringWithFormat:@"%@-v%@", styleName.lowercaseString, kStyleVersion];
 
     [titleButton setTitle:styleName forState:UIControlStateNormal];
 }
diff --git a/platform/ios/MGLMapView.mm b/platform/ios/MGLMapView.mm
index d486949175..b6519178d6 100644
--- a/platform/ios/MGLMapView.mm
+++ b/platform/ios/MGLMapView.mm
@@ -15,6 +15,7 @@
 #include <mbgl/util/geo.hpp>
 
 #import "MGLTypes.h"
+#import "NSString+MGLAdditions.h"
 #import "MGLAnnotation.h"
 #import "MGLUserLocationAnnotationView.h"
 #import "MGLUserLocation_Private.h"
@@ -43,7 +44,7 @@ const std::string &defaultCacheDatabase() {
 static dispatch_once_t loadGLExtensions;
 
 NSString *const MGLDefaultStyleName = @"Emerald";
-NSString *const MGLStyleVersion = @"v7";
+NSString *const MGLStyleVersion = @"7";
 NSString *const MGLDefaultStyleMarkerSymbolName = @"default_marker";
 
 const NSTimeInterval MGLAnimationDuration = 0.3;
@@ -106,7 +107,7 @@ mbgl::DefaultFileSource *mbglFileSource = nullptr;
 
     if (self && [self commonInit])
     {
-        if (accessToken) [self setAccessToken:accessToken];
+        [self setAccessToken:accessToken];
 
         if (styleJSON || accessToken)
         {
@@ -126,8 +127,8 @@ mbgl::DefaultFileSource *mbglFileSource = nullptr;
     
     if (self && [self commonInit])
     {
-        if (accessToken) [self setAccessToken:accessToken];
-        if (styleName) [self useBundledStyleNamed:styleName];
+        [self setAccessToken:accessToken];
+        if (styleName) [self setStyleName:styleName];
     }
     
     return self;
@@ -163,22 +164,22 @@ mbgl::DefaultFileSource *mbglFileSource = nullptr;
     return nil;
 }
 
+- (NSString *)accessToken
+{
+    return @(mbglMap->getAccessToken().c_str()).mgl_stringOrNilIfEmpty;
+}
+
 - (void)setAccessToken:(NSString *)accessToken
 {
-    if (accessToken)
-    {
-        mbglMap->setAccessToken((std::string)[accessToken UTF8String]);
-        [MGLMapboxEvents setToken:accessToken];
-    }
+    mbglMap->setAccessToken((std::string)[accessToken UTF8String]);
+    [MGLMapboxEvents setToken:accessToken.mgl_stringOrNilIfEmpty];
 }
 
 - (void)setStyleJSON:(NSString *)styleJSON
 {
     if ( ! styleJSON)
     {
-        [self useBundledStyleNamed:[[[MGLDefaultStyleName lowercaseString]
-                                        stringByAppendingString:@"-"]
-                                        stringByAppendingString:MGLStyleVersion]];
+        [self setStyleName:[NSString stringWithFormat:@"%@-v%@", MGLDefaultStyleName.lowercaseString, MGLStyleVersion]];
     }
     else
     {
@@ -186,6 +187,12 @@ mbgl::DefaultFileSource *mbglFileSource = nullptr;
     }
 }
 
+- (NSURL *)styleURL
+{
+    NSString *styleURLString = @(mbglMap->getStyleURL().c_str()).mgl_stringOrNilIfEmpty;
+    return styleURLString ? [NSURL URLWithString:styleURLString] : nil;
+}
+
 - (void)setStyleURL:(NSURL *)styleURL
 {
     std::string styleURLString([[styleURL absoluteString] UTF8String]);
@@ -1322,7 +1329,21 @@ CLLocationCoordinate2D latLngToCoordinate(mbgl::LatLng latLng)
     return [NSArray arrayWithArray:_bundledStyleNames];
 }
 
-- (void)useBundledStyleNamed:(NSString *)styleName
+- (NSString *)styleName
+{
+    NSURL *styleURL = self.styleURL;
+    NSString *styleName;
+    if ([styleURL.scheme isEqualToString:@"asset"])
+    {
+        styleName = styleURL.lastPathComponent.stringByDeletingPathExtension;
+    }
+    else if ([styleURL.scheme isEqualToString:@"mapbox"]) {
+        styleName = styleURL.host;
+    }
+    return styleName.mgl_stringOrNilIfEmpty;
+}
+
+- (void)setStyleName:(NSString *)styleName
 {
     NSString *hybridStylePrefix = @"hybrid-";
     BOOL isHybrid = [styleName hasPrefix:hybridStylePrefix];
diff --git a/platform/ios/NSString+MGLAdditions.h b/platform/ios/NSString+MGLAdditions.h
new file mode 100644
index 0000000000..263cfc8cb7
--- /dev/null
+++ b/platform/ios/NSString+MGLAdditions.h
@@ -0,0 +1,8 @@
+#import <Foundation/Foundation.h>
+
+@interface NSString (MGLAdditions)
+
+/// Returns the receiver if non-empty or \c nil if empty.
+- (NSString *)mgl_stringOrNilIfEmpty;
+
+@end
diff --git a/platform/ios/NSString+MGLAdditions.m b/platform/ios/NSString+MGLAdditions.m
new file mode 100644
index 0000000000..d80c34cef0
--- /dev/null
+++ b/platform/ios/NSString+MGLAdditions.m
@@ -0,0 +1,10 @@
+#import "NSString+MGLAdditions.h"
+
+@implementation NSString (MGLAdditions)
+
+- (NSString *)mgl_stringOrNilIfEmpty
+{
+    return self.length ? self : nil;
+}
+
+@end
diff --git a/src/mbgl/map/map.cpp b/src/mbgl/map/map.cpp
index 09e6b08a1e..ac2be3f060 100644
--- a/src/mbgl/map/map.cpp
+++ b/src/mbgl/map/map.cpp
@@ -396,6 +396,10 @@ void Map::setup() {
     painter->setup();
 }
 
+std::string Map::getStyleURL() const {
+    return data->getStyleInfo().url;
+}
+
 void Map::setStyleURL(const std::string &url) {
     assert(Environment::currentlyOn(ThreadType::Main));
 
@@ -756,7 +760,7 @@ void Map::reloadStyle() {
                 Log::Error(Event::Setup, "loading style failed: %s", res.message.c_str());
             }
         });
-    } else {
+    } else if (!styleInfo.json.empty()) {
         // We got JSON data directly.
         loadStyleJSON(styleInfo.json, styleInfo.base);
     }