Merge pull request #2 from mluisbrown/master

Use GCD for thread safe singleton initialisation

Author: Olivier Poitrey

README.md

@@ -0,0 +1,52 @@
+# SDNetworkActivityIndicator
+
+Handle showing / hiding of the iOS network activity indicator to allow multiple concurrent threads to show / hide the indicator such that the indicator remains visible until all the requests have completed and requested the indicator to be hidden.
+
+## Requirements
+
+* iOS 5.0 or later.
+* ARC memory management.
+
+## Installation
+
+The easiest way to install it is by copying the following files to your project:
+
+* SDNetworkActivityIndicator.h
+* SDNetworkActivityIndicator.m
+
+## Usage
+
+* When you start a network activity (will show the network activity indicator):
+
+        [[SDNetworkActivityIndicator sharedActivityIndicator] startActivity];
+
+* When you finish a network activity (will hide the network activity indicator only if the number of calls to `stopActivity` matches the number of calls to `startActivity`):
+
+        [[SDNetworkActivityIndicator sharedActivityIndicator] stopActivity];
+
+* To hide the network activity indicator regardless of whether all activities have finished (without having to call `stopActivity` for each `startActivity` called):
+
+        [[SDNetworkActivityIndicator sharedActivityIndicator] stopAllActivity];
+
+
+## License
+Copyright (c) 2010 Olivier Poitrey <rs@dailymotion.com>
+ 
+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.
+

SDNetworkActivityIndicator.h

@@ -9,10 +9,6 @@
 #import <Foundation/Foundation.h>
 
 @interface SDNetworkActivityIndicator : NSObject
-{
-    @private
-    NSUInteger counter;
-}
 
 + (id)sharedActivityIndicator;
 - (void)startActivity;

SDNetworkActivityIndicator.m

@@ -8,18 +8,24 @@
 
 #import "SDNetworkActivityIndicator.h"
 
-static SDNetworkActivityIndicator *instance;
+@interface SDNetworkActivityIndicator()
+{
+    @private NSUInteger counter;
+}
+@end
+
 
 @implementation SDNetworkActivityIndicator
 
-+ (id)sharedActivityIndicator
++ (instancetype) sharedActivityIndicator
 {
-    if (instance == nil)
-    {
-        instance = [[SDNetworkActivityIndicator alloc] init];
-    }
-
-    return instance;
+    static id _sharedInstance = nil;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        _sharedInstance = [[self alloc] init];
+    });
+    
+    return _sharedInstance;
 }
 
 - (id)init
@@ -36,11 +42,8 @@ - (void)startActivity
 {
     @synchronized(self)
     {
-        if (counter == 0)
-        {
-            [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
-        }
         counter++;
+        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];
     }
 }