**Core Foundation** is the C-level API, which provides CFString, CFDictionary and the like.

**Foundation** is Objective-C, which provides NSString, NSDictionary, etc.

CoreFoundation is written in C while Foundation is written in Objective-C;

Foundation has _a lot_ more classes;

CoreFoundation is the common base of Foundation and [Carbon](https://en.wikipedia.org/wiki/Carbon_(API)).

# A little history

Ref: http://ridiculousfish.com/blog/posts/bridge.html

Mac OS 9 and NEXTSTEP merged to create Mac OS X. And **Core Foundation** was created as a common ground for classic Mac toolbox and OPENSTEP(Which I believe is the toolbox for NEXTSTEP).

Classic Mac toolbox evolved and became Carbon.

OPENSTEP evolved and became Cocoa which includes **Foundation**.

So I conclude that, **Core Foundation** has much longer history and it is the foundation of **Foundation**. Since **Foundation** is kind of high-level and modern, I will stick to it unless I need to handle some historic issues which requires **Core Foundation**.

Lets say I have two functions:

    def foo():
      return &#39;foo&#39;

    def bar():
      yield &#39;bar&#39;

The first one is a normal function, and the second is a generator function. Now I want to write something like this:

    def run(func):
      if is_generator_function(func):
         gen = func()
         gen.next()
         #... run the generator ...
      else:
         func()
         
What will a straightforward implementation of `is_generator_function()` look like? Using the `types` package I can test if  `gen` is a generator, but I wish to do so before invoking `func()`. 

Now consider the following case:

    def goo():
      if False:
         yield
      else:
         return

An invocation of `goo()` will return a generator. I presume that the python parser knows that the `goo()` function has a yield statement, and I wonder if it possible to get that information easily.

Thanks!

In python is there a way to check if a function is a &quot;generator function&quot; before calling it?

How to animate a favicon like that?

![animated favicon](http://i.stack.imgur.com/ag814.gif)

It seems to work only in Firefox.

How to animate a favicon?

I try to get the hang of it, but for now both seem the same thing to me. However, Xcode allows to create an Console App with choice of using &quot;Core Foundation&quot; or just &quot;Foundation&quot;. Maybe someone can point out the differences.

Difference between Foundation Framework and Core Foundation Framework?

<p>I try to get the hang of it, but for now both seem the same thing to me. However, Xcode allows to create an Console App with choice of using "Core Foundation" or just "Foundation". Maybe someone can point out the differences.</p>


I was reading that NSArray is just such a thing. Sounds heavy. I have 7 really fat books here on my desk about Objective-C, Cocoa and C. None of them mention Class Cluster at all, at least I can&#39;t find it in the Index at the back of the books. So what&#39;s that?

What exactly is a so called &quot;Class Cluster&quot; in Objective-C?

I have been developing an iphone application using a domain model, and have put off the persistence aspect of the app until now.  Core Data looks like a really good solution since I already have a well defined model but I am running into a snag with my existing unit tests.

Here is simple example of what I have now:

    - (void)test_full_name_returns_correct_string {
        Patient *patient = [[Patient alloc] init];  
        patient.firstName = @&quot;charlie&quot;;
        patient.lastName = @&quot;chaplin&quot;;
        STAssertTrue([[patient fullName] isEqualToString:@&quot;charlie chaplin&quot;], @&quot;should have matched full name&quot;);
    }  

How can I make this work once my Patient object extends from NSManagedObject and uses @dynamic for the firstName and lastName properties?

Has anyone else run into this type of this with Core Data?  Thanks.


How to unit test my models now that I am using Core Data?

What is the most efficient/recommended way of comparing two NSDates?  I would like to be able to see if both dates are on the same day, irrespective of the time and have started writing some code that uses the timeIntervalSinceDate: method within the NSDate class and gets the integer of this value divided by the number of seconds in a day.  This seems long winded and I feel like I am missing something obvious.

The code I am trying to fix is:

    if (!([key compare:todaysDate] == NSOrderedDescending))
    {
        todaysDateSection = [eventSectionsArray count] - 1;
    }

where key and todaysDate are NSDate objects and todaysDate is creating using:

    NSDate *todaysDate = [[NSDate alloc] init];

Regards

Dave 

Comparing two NSDates and ignoring the time component

I need the ability to convert an `NSDate` value to a GMT Date.

How can I go about converting an `NSDate` value to a GMT formatted `NSDate` value, independent of whatever date locale settings the iPhone device is using?


NSDate - Convert Date to GMT

Does anyone know how can I use my custom subclass of `UINavigationBar` if I instantiate `UINavigationController` programmatically (without IB)? 

Drag a `UINavigationController` in IB show me an under Navigation Bar and using Identity Inspectory I can change class type and set my own subclass of `UINavigationBar` but programmatically I can&#39;t, `navigationBar` property of Navigation Controller is readonly...

What should I do to customize the navigation bar programmatically? Is IB more &quot;powerful&quot; than &quot;code&quot;? I believed all that can be done in IB could be done also programmatically.


Set a custom subclass of UINavigationBar in UINavigationController programmatically

Some code I am unit testing needs to load a resource file. It contains the following line:

    NSString *path = [[NSBundle mainBundle] pathForResource:@&quot;foo&quot; ofType:@&quot;txt&quot;];

In the app it runs just fine, but when run by the unit testing framework `pathForResource:` returns nil, meaning it could not locate `foo.txt`.

I&#39;ve made sure that `foo.txt` is included in the **Copy Bundle Resources** build phase of the unit test target, so why can&#39;t it find the file?

Why can&#39;t code inside unit tests find bundle resources?

I&#39;m supporting 10.4+ by picking the most-current API at runtime:

    if ([fileManager respondsToSelector:@selector(removeItemAtPath:error:)])
    	[fileManager removeItemAtPath:downloadDir error:NULL];
    else
    	[fileManager removeFileAtPath:downloadDir handler:nil];

In this case, 10.5 and up will use `removeItemAtPath:error:` and 10.4 will use `removeFileAtPath:handler:`. Great, but I still get compiler warnings for the old methods:

    warning: &#39;removeFileAtPath:handler:&#39; is deprecated [-Wdeprecated-declarations]

Is there a syntax of `if([… respondsToSelector:@selector(…)]){ … } else { … }` that hints the compiler (Clang) to not warn on that line?

If not, is there a way to tag that line to be ignored for `-Wdeprecated-declarations`?

---

After seeing some of the answers, let me clarify that confusing the compiler into not knowing what I&#39;m doing is not a valid solution.

Suppressing &quot;&#39;…&#39; is deprecated&quot; when using respondsToSelector

Snow Leopard introduced many new methods to use NSURL objects to refer to files, not pathnames or Core Services&#39; FSRefs.

However, there&#39;s one task I can&#39;t find a URL-based method for: Testing whether a file exists. I&#39;m looking for a URL-based version of [-\[NSFileManager `fileExistsAtPath:`\]](http://developer.apple.com/mac/library/documentation/Cocoa/Reference/Foundation/Classes/NSFileManager_Class/Reference/Reference.html#//apple_ref/occ/instm/NSFileManager/fileExistsAtPath:). Like that method, it should return `YES` if the URL describes anything, whether it&#39;s a regular file, a directory, or anything else.

I could attempt to look up various [resource values](http://developer.apple.com/mac/library/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/Reference/Reference.html#//apple_ref/occ/instm/NSURL/resourceValuesForKeys:error:), but none of them are explicitly guaranteed to not exist if the file doesn&#39;t, and some of them (e.g., [NSURLEffectiveIconKey](http://developer.apple.com/mac/library/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/Reference/Reference.html#//apple_ref/doc/c_ref/NSURLEffectiveIconKey)) could be costly if it does.

I could just use NSFileManager&#39;s `fileExistsAtPath:`, but if there&#39;s a more modern method, I&#39;d prefer to use that.

Is there a simple method or function in Cocoa, CF, or Core Services that&#39;s guaranteed/documented to tell me whether a given file (or file-reference) URL refers to a file-system object that exists?


Testing file existence using NSURL

I want to alter the `anchorPoint`, but keep the view in the same place.
I&#39;ve tried `NSLog`-ing `self.layer.position` and `self.center` and they both stay the same regardless of changes to the anchorPoint. Yet my view moves!

Any tips on how to do this?

		
    self.layer.anchorPoint = CGPointMake(0.5, 0.5);
    NSLog(@&quot;center point: %f %f&quot;, self.layer.position.x, self.layer.position.y);
    self.layer.anchorPoint = CGPointMake(1, 1);
    NSLog(@&quot;center point: %f %f&quot;, self.layer.position.x, self.layer.position.y);
    			
The output is:

    2009-12-27 20:43:24.161 Type[11289:207] center point: 272.500000 242.500000
    2009-12-27 20:43:24.162 Type[11289:207] center point: 272.500000 242.500000

Changing my CALayer&#39;s anchorPoint moves the view

When we do multitouch with two fingers in a UIScrollView, we get two CG points. I want to find the distance between them. Then when again we do the pinch(inside or outside), Then we will again get two points. Then after finding the distance again between these two points , I want to decide whether I pinched in or out. If i have pinched in, surely the new distance will be lesser and vice versa.

But don&#39;t know how to find an accurate measurement for the distance between 2 points for doing comparison ? Is anyone having idea about this ?

How to find the distance between two CG points?

I am calling `MFMailComposeViewController` from a `UITableViewController`.
Problem is the delegate method is never called when I select *Cancel* or *Send* button in Mail compose window: 

    mailComposeController:(MFMailComposeViewController*)controllerdidFinishWithResult 

Here is the table view class:

    @implementation DetailsTableViewController
    - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
        if (indexPath.section==0 &amp;&amp; indexPath.row==4) {
    		//SEND MAIL
    		MFMailComposeViewController *controller = [[MFMailComposeViewController alloc] init];
    		controller.mailComposeDelegate = self;
    		if ([MFMailComposeViewController canSendMail]) {
    			[controller setSubject:[NSString stringWithFormat:@&quot;Ref %@&quot;,[item objectForKey:@&quot;reference&quot;]]];
    			[controller setMessageBody:@&quot; &quot; isHTML:NO]; 
    			[controller setToRecipients:[NSArray arrayWithObject:[item objectForKey:@&quot;email&quot;]]]; 
    			[self presentModalViewController:controller animated:YES];
    		}
    		[controller release];		
    	}
    }
    
    - (void)mailComposeController:(MFMailComposeViewController*)controllerdidFinishWithResult:(MFMailComposeResult)result error:(NSError*)error {
        // NEVER REACHES THIS PLACE
    	[self dismissModalViewControllerAnimated:YES];
    	NSLog (@&quot;mail finished&quot;);
    }
    


The application doesn&#39;t crash. After the Cancel or Send button is pressed, the Compose Window stays on the screen with buttons disabled. I can exit application pressing Home key.

I am able to open other Modal Views form TableView but not MailCompose.


Unable to dismiss MFMailComposeViewController, delegate not called

I load a `UIImageView` with an image depending on user interaction.  When the parent view is initially displayed, no image has been selected and the imageview is black.  If the user leaves that view and comes back, the image is still there.  I&#39;ve tried

    myImageView.image = nil;

upon leaving the view but the image remains.  How can I remove the image so the `UIImageView` appears black again?

The 

&gt; UIImageView

 is connected through IB.

Removing image from UIImageView

What is the difference between `copy` and `mutableCopy` when used on either an `NSArray` or an `NSMutableArray`?


This is my understanding; is it correct?

    // ** NSArray **
    NSArray *myArray_imu = [NSArray  arrayWithObjects:@&quot;abc&quot;, @&quot;def&quot;, nil];
    
    // No copy, increments retain count, result is immutable
    NSArray *myArray_imuCopy = [myArray_imu copy];
    
    // Copys object, result is mutable 
    NSArray *myArray_imuMuta = [myArray_imu mutableCopy];
    
    // Both must be released later
    	
--- 
	
    // ** NSMutableArray **
    NSMutableArray *myArray_mut = [NSMutableArray arrayWithObjects:@&quot;A&quot;, @&quot;B&quot;, nil];
    	
    // Copys object, result is immutable
    NSMutableArray *myArray_mutCopy = [myArray_mut copy];
    
    // Copys object, result is mutable
    NSMutableArray *myArray_mutMuta = [myArray_mut mutableCopy];

    // Both must be released later
    

How do copy and mutableCopy apply to NSArray and NSMutableArray?

I need to extract the contents of the title tag from an HTML page displayed in a UIWebView. What is the most robust means of doing so?

I know I can do:

    - (void)webViewDidFinishLoad:(UIWebView *)webView{
    	NSString *theTitle=[webView stringByEvaluatingJavaScriptFromString:@&quot;document.title&quot;];
    }

However, that only works if javascript is enabled. 

Alternatively, I could just scan the text of the HTML code for the title but that feels a bit cumbersome and might prove fragile if the page&#39;s authors got freaky with their code. If it comes to that, what&#39;s the best method to use for processing the html text within the iPhone API?

I feel that I&#39;ve forgotten something obvious. Is there a better method than these two choices? 

Update:
-------

Following from the answer to this question: [UIWebView: Can You Disable Javascript?][1] there appears to be no way to turn off Javascript in UIWebView. Therefore the Javascript method above will always work. 

  [1]: https://stackoverflow.com/questions/2302975/uiwebview-can-you-disable-javascript

How to Get the Title of a HTML Page Displayed in UIWebView?

I need to check if an dict has a key or not. How?

How to check if an NSDictionary or NSMutableDictionary contains a key?

how to calculate the age based on the birth date in this format 6/24/1976 mon/date/year...


How to calculate the age based on NSDate

How can an object be added at a specific index of an `NSMutableArray`?

How is an object added to the front of the array?

Adding an object at a specific index of an NSMutableArray

I need to create a CGSize to compute text height of an arbitrary text with arbitrary length. UIKit has this nice method -sizeWithFont:constrainedToSize: and my text is only constrained in width, but not in height.

For this, I need to set the maximum possible CGFloat for the height.

Is there a constant like &quot;CGFloatMax&quot;?

Is there a constant for the maximum CGFloat value?

I have a small sqlitedb in my iOS device. When a user presses a button, I fetch the data from sqlite &amp; show it to user.

This fetching part I want to do it in a background thread (to not block the UI main thread). I do this like so - 

`[self performSelectorInBackground:@selector(getResultSetFromDB:) withObject:docids];`

After the fetching &amp; a little bit of processing, I need to update the UI. But since (as a good practice) we should not perform UI updation from background threads. I call a `selector` on mainthread like so - 

`[self performSelectorOnMainThread:@selector(showResults) withObject:nil waitUntilDone:NO];`

But my App crashes in the first step. i.e. starting a background thread. Is this not a way to start background threads in iOS? 

**UPDATE 1:** After `[self performSelectorInBackground....` I get this stacktrace, no info what so ever - 

![enter image description here][1]

**UPDATE 2:** I even tried, starting a background thread like so - 
`[NSThread detachNewThreadSelector:@selector(getResultSetFromDB:) toTarget:self withObject:docids];` but still I get same stacktrace.

Just so that I clarify, when I perform this operation on main thread everything runs smooth...

**UPDATE 3** This is the method I am trying to run from background 

    - (void)getResultSetFromDB:(NSMutableArray *)toProceessDocids
    {
        SpotMain *mirror = [[SpotMain alloc] init];
        NSMutableArray *filteredDocids = toProceessDocids;
    
        if(![gMediaBucket isEqualToString:@&quot;&quot;])
            filteredDocids = [mirror FetchDocIdsForMediaBucketWithDocID:filteredDocids mBucket:gMediaBucket numRes:-1];
        if(![gMediaType isEqualToString:@&quot;&quot;])
            filteredDocids = [mirror FetchDocIdsForMediaType:filteredDocids mediaType:gMediaType numRes:-1];
        if(![gPlatform isEqualToString:@&quot;&quot;])
            filteredDocids = [mirror FetchDocIdsForPlatformID:filteredDocids platformId:@&quot;1&quot; numRes:-1];
        
        self.resultSet = [mirror FetchObjectFromDocid:filteredDocids];
        [filteredDocids release];
        [mirror release];
    
        [self performSelectorOnMainThread:@selector(showResults) withObject:nil waitUntilDone:NO];
        return;
    }

  [1]: http://i.stack.imgur.com/C1AaS.png

iOS start Background Thread

In my iOS Swift app I want to generate random UUID (*GUID*) strings for use as a table key, and this snippet *appears* to work:

    let uuid = CFUUIDCreateString(nil, CFUUIDCreate(nil))

Is this safe? 

Or is there perhaps a better (recommended) approach?

Content Type	Original Author	Original Content on Stackoverflow
Question	openfrog	View Question on Stackoverflow
Solution 1 - Objective C	amrox	View Answer on Stackoverflow
Solution 2 - Objective C	Georg Schölly	View Answer on Stackoverflow
Solution 3 - Objective C	Tyler Liu	View Answer on Stackoverflow

Difference between Foundation Framework and Core Foundation Framework?

Objective C Problem Overview

Objective C Solutions

Solution 1 - Objective C

Solution 2 - Objective C

Solution 3 - Objective C

A little history

How to animate a favicon?

In python is there a way to check if a function is a "generator function" before calling it?

Attributions