fixes #85: add zoom/pan background grid view when no background image

+//
+//  RMTileLoadingView.h
+//  MapView
+//
+//  Created by Justin R. Miller on 8/15/12.
+//  Copyright 2012 MapBox.
+//
+
+#import <UIKit/UIKit.h>
+
+@interface RMLoadingTileView : UIScrollView
+
+@property (nonatomic, assign) BOOL mapZooming;
+
+@end

+//
+//  RMTileLoadingView.m
+//  MapView
+//
+//  Created by Justin R. Miller on 8/15/12.
+//  Copyright 2012 MapBox.
+//
+
+#import "RMLoadingTileView.h"
+
+@implementation RMLoadingTileView
+{
+    UIView *_contentView;
+}
+
+@synthesize mapZooming=_mapZooming;
+
+- (id)initWithFrame:(CGRect)frame
+{
+    self = [super initWithFrame:frame];
+
+    if (self)
+    {
+        NSAssert([[NSBundle mainBundle] pathForResource:@"LoadingTile" ofType:@"png"], @"Unable to find necessary graphical assets (copy from framework 'Resources' folder)");
+
+        _contentView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, frame.size.width * 3, frame.size.height * 3)];
+        [self addSubview:_contentView];
+
+        [self setMapZooming:YES];
+        
+        self.userInteractionEnabled = NO;
+        self.showsHorizontalScrollIndicator = NO;
+        self.showsVerticalScrollIndicator = NO;
+    }
+    
+    return self;
+}
+
+- (void)dealloc
+{
+    [_contentView release]; _contentView = nil;
+    [super dealloc];
+}
+
+- (void)setMapZooming:(BOOL)zooming
+{
+    if (zooming)
+    {
+        _contentView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"LoadingTileZoom.png"]];
+    }
+    else
+    {
+        _contentView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"LoadingTile.png"]];
+        
+        _contentView.frame = CGRectMake(0, 0, self.frame.size.width * 3, self.frame.size.height * 3);
+        self.contentSize = _contentView.bounds.size;
+        self.contentOffset = CGPointMake(self.frame.size.width, self.frame.size.height);
+    }
+    
+    _mapZooming = zooming;
+}
+
+- (void)setContentOffset:(CGPoint)contentOffset
+{
+    CGPoint newContentOffset = contentOffset;
+    
+    if (newContentOffset.x > 2 * self.contentSize.width / 3)
+    {
+        newContentOffset.x = self.bounds.size.width;
+    }
+    else if (newContentOffset.x < self.contentSize.width / 3)
+    {
+        newContentOffset.x = self.bounds.size.width * 2;
+    }
+
+    if (newContentOffset.y > 2 * self.contentSize.height / 3)
+    {
+        newContentOffset.y = self.bounds.size.height;
+    }
+    else if (newContentOffset.y < self.contentSize.height / 3)
+    {
+        newContentOffset.y = self.bounds.size.height * 2;
+    }
+
+    [super setContentOffset:newContentOffset];
+}
+
+@end

@@ -46,6 +46,7 @@
 
 #import "RMMapTiledLayerView.h"
 #import "RMMapOverlayView.h"
+#import "RMLoadingTileView.h"
 
 #import "RMUserLocation.h"
 
@@ -135,6 +136,7 @@
     RMMapScrollView *_mapScrollView;
     RMMapOverlayView *_overlayView;
     UIView *_tiledLayersSuperview;
+    RMLoadingTileView *_loadingTileView;
 
     RMProjection *_projection;
     RMFractalTileProjection *_mercatorToTileProjection;
@@ -241,9 +243,16 @@
 
     [self setTileCache:[[[RMTileCache alloc] init] autorelease]];
 
-    [self setBackgroundView:[[[UIView alloc] initWithFrame:[self bounds]] autorelease]];
     if (backgroundImage)
+    {
+        [self setBackgroundView:[[[UIView alloc] initWithFrame:[self bounds]] autorelease]];
         self.backgroundView.layer.contents = (id)backgroundImage.CGImage;
+    }
+    else
+    {
+        _loadingTileView = [[[RMLoadingTileView alloc] initWithFrame:self.bounds] autorelease];
+        [self setBackgroundView:_loadingTileView];
+    }
 
     if (minZoomLevel < newTilesource.minZoom) minZoomLevel = newTilesource.minZoom;
     if (maxZoomLevel > newTilesource.maxZoom) maxZoomLevel = newTilesource.maxZoom;
@@ -1214,6 +1223,9 @@
     [self registerZoomEventByUser:(scrollView.pinchGestureRecognizer.state == UIGestureRecognizerStateBegan)];
 
     _mapScrollViewIsZooming = YES;
+
+    if (_loadingTileView)
+        _loadingTileView.mapZooming = YES;
 }
 
 - (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale
@@ -1224,6 +1236,19 @@
     _mapScrollViewIsZooming = NO;
 
     [self correctPositionOfAllAnnotations];
+
+    if (_loadingTileView)
+        _loadingTileView.mapZooming = NO;
+}
+
+- (void)scrollViewDidScroll:(UIScrollView *)scrollView
+{
+    if (_loadingTileView)
+    {
+        CGSize delta = CGSizeMake(scrollView.contentOffset.x - _lastContentOffset.x, scrollView.contentOffset.y - _lastContentOffset.y);
+        CGPoint newOffset = CGPointMake(_loadingTileView.contentOffset.x + delta.width, _loadingTileView.contentOffset.y + delta.height);
+        _loadingTileView.contentOffset = newOffset;
+    }
 }
 
 - (void)scrollViewDidZoom:(UIScrollView *)scrollView

@@ -21,7 +21,7 @@
     if ( ! (self = [super initWithMapView:aMapView coordinate:aCoordinate andTitle:aTitle]))
         return nil;
 
-    NSAssert([[NSBundle mainBundle] pathForResource:@"TrackingDot" ofType:@"png"], @"Unable to find necessary user location graphical assets (copy from MapView/Map/Resources)");
+    NSAssert([[NSBundle mainBundle] pathForResource:@"TrackingDot" ofType:@"png"], @"Unable to find necessary graphical assets (copy from framework 'Resources' folder)");
     
     layer = [[RMMarker alloc] initWithUIImage:[UIImage imageNamed:@"TrackingDot.png"]];
 

@@ -103,6 +103,8 @@
 		DD5A200B15CAD09400FE4157 /* GRMustache.h in Headers */ = {isa = PBXBuildFile; fileRef = DD5A200A15CAD09400FE4157 /* GRMustache.h */; };
 		DD6380DD152E72880074E66E /* RMMapBoxSource.h in Headers */ = {isa = PBXBuildFile; fileRef = DD6380DB152E72880074E66E /* RMMapBoxSource.h */; };
 		DD6380DE152E72880074E66E /* RMMapBoxSource.m in Sources */ = {isa = PBXBuildFile; fileRef = DD6380DC152E72880074E66E /* RMMapBoxSource.m */; };
+		DD5FA1EB15E2B020004EB6C5 /* RMLoadingTileView.h in Headers */ = {isa = PBXBuildFile; fileRef = DD5FA1E915E2B020004EB6C5 /* RMLoadingTileView.h */; };
+		DD5FA1EC15E2B020004EB6C5 /* RMLoadingTileView.m in Sources */ = {isa = PBXBuildFile; fileRef = DD5FA1EA15E2B020004EB6C5 /* RMLoadingTileView.m */; };
 		DD8CDB4A14E0507100B73EB9 /* RMMapQuestOSMSource.h in Headers */ = {isa = PBXBuildFile; fileRef = DD8CDB4814E0507100B73EB9 /* RMMapQuestOSMSource.h */; };
 		DD8CDB4B14E0507100B73EB9 /* RMMapQuestOSMSource.m in Sources */ = {isa = PBXBuildFile; fileRef = DD8CDB4914E0507100B73EB9 /* RMMapQuestOSMSource.m */; };
 		DD8FD7541559E4A40044D96F /* RMUserLocation.h in Headers */ = {isa = PBXBuildFile; fileRef = DD8FD7521559E4A40044D96F /* RMUserLocation.h */; };
@@ -228,9 +230,12 @@
 		DD2B375414CF8197008DE8CB /* RMMBTilesSource.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RMMBTilesSource.m; sourceTree = "<group>"; };
 		DD3BEF7715913C55007892D8 /* RMAttributionViewController.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RMAttributionViewController.h; sourceTree = "<group>"; };
 		DD3BEF7815913C55007892D8 /* RMAttributionViewController.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RMAttributionViewController.m; sourceTree = "<group>"; };
+		DD49B8A815E2CE4E0055CCEE /* LoadingTileZoom.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; name = LoadingTileZoom.png; path = Resources/LoadingTileZoom.png; sourceTree = "<group>"; };
+		DD49B8A915E2CE4E0055CCEE /* LoadingTile.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; name = LoadingTile.png; path = Resources/LoadingTile.png; sourceTree = "<group>"; };
 		DD5A200815CAD03700FE4157 /* libGRMustache4-iOS.a */ = {isa = PBXFileReference; lastKnownFileType = archive.ar; name = "libGRMustache4-iOS.a"; path = "GRMustache/lib/libGRMustache4-iOS.a"; sourceTree = "<group>"; };
 		DD5A200A15CAD09400FE4157 /* GRMustache.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = GRMustache.h; path = GRMustache/include/GRMustache.h; sourceTree = "<group>"; };
-		DD624B4315B4EB53004524C4 /* loading.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; name = loading.png; path = Resources/loading.png; sourceTree = "<group>"; };
+		DD5FA1E915E2B020004EB6C5 /* RMLoadingTileView.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RMLoadingTileView.h; sourceTree = "<group>"; };
+		DD5FA1EA15E2B020004EB6C5 /* RMLoadingTileView.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RMLoadingTileView.m; sourceTree = "<group>"; };
 		DD8CDB4814E0507100B73EB9 /* RMMapQuestOSMSource.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RMMapQuestOSMSource.h; sourceTree = "<group>"; };
 		DD8CDB4914E0507100B73EB9 /* RMMapQuestOSMSource.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RMMapQuestOSMSource.m; sourceTree = "<group>"; };
 		DD8FD7521559E4A40044D96F /* RMUserLocation.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RMUserLocation.h; sourceTree = "<group>"; };
@@ -363,6 +368,8 @@
 				1609AF8D14068B09008344B7 /* RMMapOverlayView.m */,
 				16F3581915864135003A3AD9 /* RMMapScrollView.h */,
 				16F3581A15864135003A3AD9 /* RMMapScrollView.m */,
+				DD5FA1E915E2B020004EB6C5 /* RMLoadingTileView.h */,
+				DD5FA1EA15E2B020004EB6C5 /* RMLoadingTileView.m */,
 			);
 			name = "Tile Layer & Overlay";
 			sourceTree = "<group>";
@@ -509,9 +516,10 @@
 		DD8FD7581559EDA80044D96F /* Resources */ = {
 			isa = PBXGroup;
 			children = (
-				DD624B4315B4EB53004524C4 /* loading.png */,
 				DD8FD7631559EE120044D96F /* HeadingAngleSmall.png */,
 				DD8FD7641559EE120044D96F /* HeadingAngleSmall@2x.png */,
+				DD49B8A915E2CE4E0055CCEE /* LoadingTile.png */,
+				DD49B8A815E2CE4E0055CCEE /* LoadingTileZoom.png */,
 				DD8FD7651559EE120044D96F /* TrackingDot.png */,
 				DD8FD7661559EE120044D96F /* TrackingDot@2x.png */,
 				DD8FD76C1559EE120044D96F /* TrackingDotHalo.png */,
@@ -602,6 +610,7 @@
 				161E563A1594664E00B00BB6 /* RMOpenSeaMapLayer.h in Headers */,
 				1656665515A1DF7900EF3DC7 /* RMCoordinateGridSource.h in Headers */,
 				DD5A200B15CAD09400FE4157 /* GRMustache.h in Headers */,
+				DD5FA1EB15E2B020004EB6C5 /* RMLoadingTileView.h in Headers */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -719,6 +728,7 @@
 				16FBF07715936BF1004ECAD1 /* RMTileSourcesContainer.m in Sources */,
 				161E563B1594664E00B00BB6 /* RMOpenSeaMapLayer.m in Sources */,
 				1656665615A1DF7900EF3DC7 /* RMCoordinateGridSource.m in Sources */,
+				DD5FA1EC15E2B020004EB6C5 /* RMLoadingTileView.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};