Adds NGDragGestureRecognizer and MainViewController which demos it.

DragGestureRecognizer.xcodeproj/project.pbxproj

@@ -20,6 +20,7 @@
 		2EBB3DBE18EB638C007A7E63 /* InfoPlist.strings in Resources */ = {isa = PBXBuildFile; fileRef = 2EBB3DBC18EB638C007A7E63 /* InfoPlist.strings */; };
 		2EBB3DC018EB638C007A7E63 /* DragGestureRecognizerTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 2EBB3DBF18EB638C007A7E63 /* DragGestureRecognizerTests.m */; };
 		2EBB3DCB18EB63E2007A7E63 /* MainViewController.m in Sources */ = {isa = PBXBuildFile; fileRef = 2EBB3DCA18EB63E2007A7E63 /* MainViewController.m */; };
+		2EBB3DCE18EB64DB007A7E63 /* NGDragGestureRecognizer.m in Sources */ = {isa = PBXBuildFile; fileRef = 2EBB3DCD18EB64DB007A7E63 /* NGDragGestureRecognizer.m */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -51,6 +52,8 @@
 		2EBB3DBF18EB638C007A7E63 /* DragGestureRecognizerTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = DragGestureRecognizerTests.m; sourceTree = "<group>"; };
 		2EBB3DC918EB63E2007A7E63 /* MainViewController.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MainViewController.h; sourceTree = "<group>"; };
 		2EBB3DCA18EB63E2007A7E63 /* MainViewController.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MainViewController.m; sourceTree = "<group>"; };
+		2EBB3DCC18EB64DB007A7E63 /* NGDragGestureRecognizer.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = NGDragGestureRecognizer.h; sourceTree = "<group>"; };
+		2EBB3DCD18EB64DB007A7E63 /* NGDragGestureRecognizer.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = NGDragGestureRecognizer.m; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -114,6 +117,8 @@
 				2EBB3DAA18EB638C007A7E63 /* AppDelegate.m */,
 				2EBB3DAC18EB638C007A7E63 /* Images.xcassets */,
 				2EBB3DA118EB638C007A7E63 /* Supporting Files */,
+				2EBB3DCC18EB64DB007A7E63 /* NGDragGestureRecognizer.h */,
+				2EBB3DCD18EB64DB007A7E63 /* NGDragGestureRecognizer.m */,
 				2EBB3DC918EB63E2007A7E63 /* MainViewController.h */,
 				2EBB3DCA18EB63E2007A7E63 /* MainViewController.m */,
 			);
@@ -246,6 +251,7 @@
 			files = (
 				2EBB3DAB18EB638C007A7E63 /* AppDelegate.m in Sources */,
 				2EBB3DCB18EB63E2007A7E63 /* MainViewController.m in Sources */,
+				2EBB3DCE18EB64DB007A7E63 /* NGDragGestureRecognizer.m in Sources */,
 				2EBB3DA718EB638C007A7E63 /* main.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

DragGestureRecognizer/MainViewController.m

@@ -7,43 +7,63 @@
 //
 
 #import "MainViewController.h"
+#import "NGDragGestureRecognizer.h"
+
 
 @interface MainViewController ()
 
+@property (strong, nonatomic) UIView * containerView;
+@property (strong, nonatomic) UIView * draggableView;
+
 @end
 
-@implementation MainViewController
 
-- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
-{
-    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
-    if (self) {
-        // Custom initialization
-    }
-    return self;
-}
+@implementation MainViewController
 
 - (void)viewDidLoad
 {
     [super viewDidLoad];
-    // Do any additional setup after loading the view.
+    
+    CGFloat diameter = 44;
+    
+    for (NSInteger row = 1; row < 5; row++) {
+        for (NSInteger column = 1; column < 4; column++) {
+            
+            UIView * view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, diameter, diameter)];
+            view.center = CGPointMake(column * 80, row * 96);
+            view.backgroundColor = [UIColor whiteColor];
+            view.layer.cornerRadius = diameter / 2;
+            view.layer.borderColor = [UIColor colorWithRed:0.0902 green:0.5765 blue:0.7725 alpha:1.0000].CGColor;
+            view.layer.borderWidth = 3;
+            
+            NGDragGestureRecognizer * gestureRecognizer = [[NGDragGestureRecognizer alloc] initWithTarget:self action:@selector(handleDragGesture:)];
+            [view addGestureRecognizer:gestureRecognizer];
+            [self.view addSubview:view];
+        }
+    }
 }
 
-- (void)didReceiveMemoryWarning
+- (void)handleDragGesture:(NGDragGestureRecognizer *)gestureRecognizer
 {
-    [super didReceiveMemoryWarning];
-    // Dispose of any resources that can be recreated.
+    UIView * draggedView = gestureRecognizer.view;
+    UIView * superview = draggedView.superview;
+    
+    if (gestureRecognizer.state == UIGestureRecognizerStateBegan) {
+        [gestureRecognizer setTranslation:draggedView.center inView:superview];
+        [superview bringSubviewToFront:draggedView];
+        draggedView.layer.borderColor = [UIColor colorWithRed:0.2784 green:0.7412 blue:0.9412 alpha:1.0000].CGColor;
+        return;
+    }
+    
+    if (gestureRecognizer.state == UIGestureRecognizerStateChanged) {
+        draggedView.center = [gestureRecognizer translationInView:superview];
+        return;
+    }
+    
+    if (gestureRecognizer.state == UIGestureRecognizerStateEnded || gestureRecognizer.state == UIGestureRecognizerStateCancelled) {
+        draggedView.layer.borderColor = [UIColor colorWithRed:0.0902 green:0.5765 blue:0.7725 alpha:1.0000].CGColor;
+        return;
+    }
 }
 
-/*
-#pragma mark - Navigation
-
-// In a storyboard-based application, you will often want to do a little preparation before navigation
-- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
-{
-    // Get the new view controller using [segue destinationViewController].
-    // Pass the selected object to the new view controller.
-}
-*/
-
 @end

DragGestureRecognizer/NGDragGestureRecognizer.h

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2014 Wojciech Nagrodzki
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#import <UIKit/UILongPressGestureRecognizer.h>
+
+
+@interface NGDragGestureRecognizer : UILongPressGestureRecognizer
+
+/**
+ * The translation of the pan gesture in the coordinate system of the specified view.
+ * The x and y values report the total translation over time. They are not delta values from the last time that the translation was reported. 
+ * Apply the translation value to the state of the view when the gesture is first recognized—do not concatenate the value each time the handler is called.
+ * 
+ * @param view The view in whose coordinate system the translation of the long press pan gesture should be computed. 
+               If you want to adjust a view's location to keep it under the user's finger, request the translation in that view's superview's coordinate system.
+ * @return A point identifying the new location of a view in the coordinate system of its designated superview.
+ */
+- (CGPoint)translationInView:(UIView *)view;
+
+/**
+ * Sets the translation value in the coordinate system of the specified view.
+ * Changing the translation value resets the velocity of the pan.
+ * 
+ * @param translation A point that identifies the new translation value.
+ * @param view A view in whose coordinate system the translation is to occur.
+ */
+- (void)setTranslation:(CGPoint)translation inView:(UIView *)view;
+
+@end

DragGestureRecognizer/NGDragGestureRecognizer.m

@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2014 Wojciech Nagrodzki
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#import "NGDragGestureRecognizer.h"
+#import <UIKit/UIGestureRecognizerSubclass.h>
+
+
+@interface NGDragGestureRecognizer ()
+
+@property (assign, nonatomic) CGPoint initialTouchLocation;
+@property (strong, nonatomic) NSMapTable * viewsBeginLocations;
+
+@end
+
+
+@implementation NGDragGestureRecognizer
+
+#pragma mark - Public Instance Methods
+
+- (CGPoint)translationInView:(UIView *)view
+{
+    CGPoint currentLocation = [self locationInView:view];
+    NSValue * initialLocationValue = [self.viewsBeginLocations objectForKey:view];
+    CGPoint initialLocation = initialLocationValue ? initialLocationValue.CGPointValue : [[self referenceView] convertPoint:self.initialTouchLocation toView:view];
+    return CGPointMake(currentLocation.x - initialLocation.x, currentLocation.y - initialLocation.y);
+}
+
+- (void)setTranslation:(CGPoint)translation inView:(UIView *)view
+{
+    CGPoint currentLocation = [self locationInView:view];
+    CGPoint initialLocation = CGPointMake(currentLocation.x - translation.x, currentLocation.y - translation.y);
+    NSValue * initialLocationValue = [NSValue valueWithCGPoint:initialLocation];
+    [self.viewsBeginLocations setObject:initialLocationValue forKey:view];
+}
+
+#pragma mark - Overriden
+
+- (void)setState:(UIGestureRecognizerState)state
+{
+    [super setState:state];
+    
+    if (state == UIGestureRecognizerStateBegan) {
+        [self.viewsBeginLocations removeAllObjects];
+        self.initialTouchLocation = [self locationInView:[self referenceView]];
+    }
+}
+
+#pragma mark - Private Instance Methods
+
+- (NSMapTable *)viewsBeginLocations
+{
+    if (_viewsBeginLocations == nil) {
+        _viewsBeginLocations = [NSMapTable weakToStrongObjectsMapTable];
+    }
+    return _viewsBeginLocations;
+}
+
+#pragma mark - Private Methods
+
+- (UIView *)referenceView
+{
+    return self.view;
+}
+
+@end