[ios, macos] Improve snap shotter documentation. (#10020)

* [ios, macos] Improve snap shotter documentation.

* [macos] Save snapshots in correct format

* [macos] Renamed snapshot item to Export Image

* [ios, macos] Clarify Snapshotter documentation.

* [ios] Fix snapshot scale

* [macOS] Fix snapshotter 4x scaling.

* [ios] Fix snapshotter final image scale.

* [ios, macos] Update snapshotter size documentation.

* [ios, macos] Throw an exception when the snapshotter has already started.

* [ios, macos] Add snapshotter header example.

* [ios, macos] Use one of the predefined Foundation's exception names.

3 files changed, 17 insertions, 17 deletions

diff --git a/platform/ios/app/MBXSnapshotsViewController.m b/platform/ios/app/MBXSnapshotsViewController.m
index d26479f085..ab5ad97c90 100644
--- a/platform/ios/app/MBXSnapshotsViewController.m
+++ b/platform/ios/app/MBXSnapshotsViewController.m
@@ -18,27 +18,27 @@
 
 @implementation MBXSnapshotsViewController {
     // Top row
-    MGLMapSnapshotter* snapshotterTL;
-    MGLMapSnapshotter* snapshotterTM;
-    MGLMapSnapshotter* snapshotterTR;
+    MGLMapSnapshotter* topLeftSnapshotter;
+    MGLMapSnapshotter* topCenterSnapshotter;
+    MGLMapSnapshotter* topRightSnapshotter;
     
     // Bottom row
-    MGLMapSnapshotter* snapshotterBL;
-    MGLMapSnapshotter* snapshotterBM;
-    MGLMapSnapshotter* snapshotterBR;
+    MGLMapSnapshotter* bottomLeftSnapshotter;
+    MGLMapSnapshotter* bottomCenterSnapshotter;
+    MGLMapSnapshotter* bottomRightSnapshotter;
 }
 
 - (void)viewDidLoad {
     [super viewDidLoad];
 
     // Start snapshotters
-    snapshotterTL = [self startSnapshotterForImageView:_snapshotImageViewTL coordinates:CLLocationCoordinate2DMake(37.7184, -122.4365)];
-    snapshotterTM = [self startSnapshotterForImageView:_snapshotImageViewTM coordinates:CLLocationCoordinate2DMake(38.8936, -77.0146)];
-    snapshotterTR = [self startSnapshotterForImageView:_snapshotImageViewTR coordinates:CLLocationCoordinate2DMake(-13.1356, -74.2442)];
+    topLeftSnapshotter = [self startSnapshotterForImageView:_snapshotImageViewTL coordinates:CLLocationCoordinate2DMake(37.7184, -122.4365)];
+    topCenterSnapshotter = [self startSnapshotterForImageView:_snapshotImageViewTM coordinates:CLLocationCoordinate2DMake(38.8936, -77.0146)];
+    topRightSnapshotter = [self startSnapshotterForImageView:_snapshotImageViewTR coordinates:CLLocationCoordinate2DMake(-13.1356, -74.2442)];
 
-    snapshotterBL = [self startSnapshotterForImageView:_snapshotImageViewBL coordinates:CLLocationCoordinate2DMake(52.5072, 13.4247)];
-    snapshotterBM = [self startSnapshotterForImageView:_snapshotImageViewBM coordinates:CLLocationCoordinate2DMake(60.2118, 24.6754)];
-    snapshotterBR = [self startSnapshotterForImageView:_snapshotImageViewBR coordinates:CLLocationCoordinate2DMake(31.2780, 121.4286)];
+    bottomLeftSnapshotter = [self startSnapshotterForImageView:_snapshotImageViewBL coordinates:CLLocationCoordinate2DMake(52.5072, 13.4247)];
+    bottomCenterSnapshotter = [self startSnapshotterForImageView:_snapshotImageViewBM coordinates:CLLocationCoordinate2DMake(60.2118, 24.6754)];
+    bottomRightSnapshotter = [self startSnapshotterForImageView:_snapshotImageViewBR coordinates:CLLocationCoordinate2DMake(31.2780, 121.4286)];
 }
 
 - (MGLMapSnapshotter*) startSnapshotterForImageView:(UIImageView*) imageView coordinates:(CLLocationCoordinate2D) coordinates  {
@@ -46,8 +46,8 @@
     MGLMapCamera* mapCamera = [[MGLMapCamera alloc] init];
     mapCamera.pitch = 20;
     mapCamera.centerCoordinate = coordinates;
-    MGLMapSnapshotOptions* options = [[MGLMapSnapshotOptions alloc] initWithStyleURL:[NSURL URLWithString:@"mapbox://styles/mapbox/traffic-day-v2"] camera:mapCamera size:CGSizeMake(imageView.frame.size.width, imageView.frame.size.height)];
-    options.zoom = 10;
+    MGLMapSnapshotOptions* options = [[MGLMapSnapshotOptions alloc] initWithStyleURL:[MGLStyle satelliteStreetsStyleURL] camera:mapCamera size:CGSizeMake(imageView.frame.size.width, imageView.frame.size.height)];
+    options.zoomLevel = 10;
     
     // Create and start the snapshotter
     MGLMapSnapshotter* snapshotter = [[MGLMapSnapshotter alloc] initWithOptions:options];
diff --git a/platform/ios/src/UIImage+MGLAdditions.h b/platform/ios/src/UIImage+MGLAdditions.h
index 3c179d6324..22bb740242 100644
--- a/platform/ios/src/UIImage+MGLAdditions.h
+++ b/platform/ios/src/UIImage+MGLAdditions.h
@@ -8,7 +8,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (nullable instancetype)initWithMGLStyleImage:(const mbgl::style::Image *)styleImage;
 
-- (nullable instancetype)initWithMGLPremultipliedImage:(const mbgl::PremultipliedImage&&)mbglImage;
+- (nullable instancetype)initWithMGLPremultipliedImage:(const mbgl::PremultipliedImage&&)mbglImage scale:(CGFloat)scale;
 
 - (std::unique_ptr<mbgl::style::Image>)mgl_styleImageWithIdentifier:(NSString *)identifier;
 
diff --git a/platform/ios/src/UIImage+MGLAdditions.mm b/platform/ios/src/UIImage+MGLAdditions.mm
index 7cf1ed9bcc..8ab1d5c259 100644
--- a/platform/ios/src/UIImage+MGLAdditions.mm
+++ b/platform/ios/src/UIImage+MGLAdditions.mm
@@ -22,14 +22,14 @@
     return self;
 }
 
-- (nullable instancetype)initWithMGLPremultipliedImage:(const mbgl::PremultipliedImage&&)mbglImage
+- (nullable instancetype)initWithMGLPremultipliedImage:(const mbgl::PremultipliedImage&&)mbglImage scale:(CGFloat)scale
 {
     CGImageRef image = CGImageFromMGLPremultipliedImage(mbglImage.clone());
     if (!image) {
         return nil;
     }
 
-    self = [self initWithCGImage:image scale:1.0 orientation:UIImageOrientationUp];
+    self = [self initWithCGImage:image scale:scale orientation:UIImageOrientationUp];
     
     CGImageRelease(image);
     return self;