Added allowsEmptySelection property as requested in #11

AccordionView.h

@@ -46,5 +46,6 @@
 @property (nonatomic, strong) NSIndexSet *selectionIndexes;
 @property (nonatomic, strong) id <AccordionViewDelegate> delegate;
 @property (nonatomic, assign) BOOL startsClosed;
+@property (nonatomic, assign) BOOL allowsEmptySelection;
 
 @end

AccordionView.m

@@ -22,7 +22,7 @@
 @implementation AccordionView
 
 @synthesize selectedIndex, isHorizontal, animationDuration, animationCurve;
-@synthesize allowsMultipleSelection, selectionIndexes, delegate, startsClosed;
+@synthesize allowsMultipleSelection, selectionIndexes, delegate, startsClosed, allowsEmptySelection;
 
 - (id)initWithFrame:(CGRect)frame {
     self = [super initWithFrame:frame];
@@ -51,6 +51,8 @@ - (id)initWithFrame:(CGRect)frame {
         self.allowsMultipleSelection = NO;
 
         self.startsClosed = NO;
+
+        self.allowsEmptySelection = YES;
     }
 
     return self;
@@ -173,15 +175,17 @@ - (void)touchDown:(id)sender {
     if (allowsMultipleSelection) {
         NSMutableIndexSet *mis = [selectionIndexes mutableCopy];
         if ([selectionIndexes containsIndex:[sender tag]]) {
-            [mis removeIndex:[sender tag]];
+            if (self.allowsEmptySelection || [selectionIndexes count] > 1) {
+                [mis removeIndex:[sender tag]];
+            }
         } else {
             [mis addIndex:[sender tag]];
         }
 
         [self setSelectionIndexes:mis];
     } else {
         // If the touched section is already opened, close it.
-        if ([selectionIndexes firstIndex] == [sender tag]) {
+        if (([selectionIndexes firstIndex] == [sender tag]) && self.allowsEmptySelection) {
             [self setSelectionIndexes:[NSIndexSet indexSet]];
         } else {
             [self setSelectedIndex:[sender tag]];

Example/test.xcodeproj/project.xcworkspace/xcshareddata/test.xccheckout

@@ -0,0 +1,41 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDESourceControlProjectFavoriteDictionaryKey</key>
+	<false/>
+	<key>IDESourceControlProjectIdentifier</key>
+	<string>81B415EA-2485-4B70-84D9-24F6C2783DDB</string>
+	<key>IDESourceControlProjectName</key>
+	<string>test</string>
+	<key>IDESourceControlProjectOriginsDictionary</key>
+	<dict>
+		<key>4FF14784-A0E1-4E60-9D17-1B478CCAEF65</key>
+		<string>ssh://github.com/appsome/AccordionView.git</string>
+	</dict>
+	<key>IDESourceControlProjectPath</key>
+	<string>Example/test.xcodeproj/project.xcworkspace</string>
+	<key>IDESourceControlProjectRelativeInstallPathDictionary</key>
+	<dict>
+		<key>4FF14784-A0E1-4E60-9D17-1B478CCAEF65</key>
+		<string>../../..</string>
+	</dict>
+	<key>IDESourceControlProjectURL</key>
+	<string>ssh://github.com/appsome/AccordionView.git</string>
+	<key>IDESourceControlProjectVersion</key>
+	<integer>110</integer>
+	<key>IDESourceControlProjectWCCIdentifier</key>
+	<string>4FF14784-A0E1-4E60-9D17-1B478CCAEF65</string>
+	<key>IDESourceControlProjectWCConfigurations</key>
+	<array>
+		<dict>
+			<key>IDESourceControlRepositoryExtensionIdentifierKey</key>
+			<string>public.vcs.git</string>
+			<key>IDESourceControlWCCIdentifierKey</key>
+			<string>4FF14784-A0E1-4E60-9D17-1B478CCAEF65</string>
+			<key>IDESourceControlWCCName</key>
+			<string>AccordionView</string>
+		</dict>
+	</array>
+</dict>
+</plist>

Example/test/ViewController.m

@@ -68,6 +68,9 @@ - (void)viewDidLoad
 
     // Set this if you want to allow multiple selection
     [accordion setAllowsMultipleSelection:YES];
+
+    // Set this to NO if you want to have at least one open section at all times
+    [accordion setAllowsEmptySelection:YES];
 }
 
 - (void)removeSecondRow {