diff --git a/README.md b/README.md
index 87c6eab..e86389f 100644
--- a/README.md
+++ b/README.md
@@ -9,8 +9,10 @@ iOS 6 introduced the "share sheet"—a simple native interface to launch actions
 // init Readability activity
 ReadabilityActivity *rdb = [[ReadabilityActivity alloc] init];
 
-// set up activity item / action. url is a NSURL
-NSArray *activityItems = @[ReadabilityActivityAdd, url];
+NSURL *url = [NSURL URLWithSting:@"http://example.com"];
+
+// set up activity item / action
+NSArray *activityItems = @[url];
 
 // init share sheet with app-specific activity
 UIActivityViewController *shareSheet = [[UIActivityViewController alloc] initWithActivityItems:activityItems applicationActivities:@[rdb]];
diff --git a/ReadabilityActivity.h b/ReadabilityActivity.h
old mode 100644
new mode 100755
index 2476ec5..6ba1294
--- a/ReadabilityActivity.h
+++ b/ReadabilityActivity.h
@@ -7,9 +7,6 @@
 
 #import <UIKit/UIKit.h>
 
-extern NSString * const ReadabilityActivityURI;
-extern NSString * const ReadabilityActivityAdd;
-
 @interface ReadabilityActivity : UIActivity
 {
     @private NSArray *_activityItems;
diff --git a/ReadabilityActivity.m b/ReadabilityActivity.m
old mode 100644
new mode 100755
index 1c38d54..b88a82a
--- a/ReadabilityActivity.m
+++ b/ReadabilityActivity.m
@@ -7,8 +7,8 @@
 
 #import "ReadabilityActivity.h"
 
-NSString * const ReadabilityActivityURI = @"readability://";
-NSString * const ReadabilityActivityAdd = @"add";
+static NSString * const ReadabilityActivityURI = @"readability://";
+static NSString * const ReadabilityActivityAdd = @"add";
 
 @implementation ReadabilityActivity
 
@@ -22,10 +22,8 @@ - (NSString *)activityTitle
     return @"Readability";
 }
 
-- (UIImage *)activityImage
-{
-    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
-    {
+- (UIImage *)activityImage {
+    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) {
         return [UIImage imageNamed:@"Readability-activity-iPad"];
     }
     
@@ -34,6 +32,14 @@ - (UIImage *)activityImage
 
 - (BOOL)canPerformWithActivityItems:(NSArray *)activityItems
 {
+    if (![ReadabilityActivity canPerformActivity]) {
+        return NO;
+    }
+    for (NSObject *item in activityItems) {
+        if (![item isKindOfClass:[NSURL class]] && ![item isKindOfClass:[NSString class]]) {
+            return NO;
+        }
+    }
     return YES;
 }
 
@@ -42,28 +48,27 @@ - (void)prepareWithActivityItems:(NSArray *)activityItems
     _activityItems = activityItems;
 }
 
-- (void)performActivity
-{
-    if ([ReadabilityActivity canPerformActivity])
-    {
-        NSString *activityAction = _activityItems[0];
-        NSURL *activityURL = _activityItems[1];
+- (void)performActivity {
+    if ([ReadabilityActivity canPerformActivity]){
+        NSString *activityURL = nil;
         
-        NSString *readabilityURLString = [NSString stringWithFormat:@"%@%@/%@", ReadabilityActivityURI, activityAction, [activityURL absoluteString]];
-        NSURL *readabilityURL = [NSURL URLWithString:readabilityURLString];
+        if([_activityItems[0] isKindOfClass:[NSURL class]]) {
+            activityURL = [_activityItems[0] absoluteString];
+
+        } else {
+            activityURL = _activityItems[0];
+        }
         
-        [[UIApplication sharedApplication] openURL:readabilityURL];
+        NSString *readabilityURLString = [NSString stringWithFormat:@"%@%@/%@", ReadabilityActivityURI, ReadabilityActivityAdd, activityURL];
         
+        [[UIApplication sharedApplication] openURL:[NSURL URLWithString:readabilityURLString]];
         [self activityDidFinish:YES];
-    }
-    else
-    {
+    } else{
         [self activityDidFinish:NO];
     }
 }
 
-+ (BOOL)canPerformActivity
-{
++ (BOOL)canPerformActivity {
     if ([[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:ReadabilityActivityURI]])
     {
         return YES;