I found the answer: to exclude the file from ARC, use the **-fno-objc-arc** flag in build phases&gt;compile sources

&gt; the moral of this story is: once your project is in ARC and you have some files marked as no ARC, do not re-run the convert to ARC tool from Refactor&gt;Convert to ARC. It will not restore your settings even if pre-check fails.

You can restore your settings for excluded files by removing references on them and then readd  to project back

I&#39;m trying to understand the advantages of currying over partial applications in Scala. Please consider the following code:

      def sum(f: Int =&gt; Int) = (a: Int, b: Int) =&gt; f(a) + f(b)
    
      def sum2(f: Int =&gt; Int, a: Int, b: Int): Int = f(a) + f(b)

      def sum3(f: Int =&gt; Int)(a: Int, b: Int): Int = f(a) + f(b)
      
      val ho = sum({identity})
      val partial = sum2({ identity }, _, _)
      val currying = sum3({ identity })
    
      val a = currying(2, 2)
      val b = partial(2, 2)
      val c = ho(2, 2)

So, if I can calculate partially applied function that easy, what are the advantages of currying?

Usefulness (as in practical applications) of Currying v.s. Partial Application in Scala

I&#39;ve got a collection of Duck objects and I&#39;d like to **sort them using multiple keys**.

    class Duck {
        DuckAge age; //implements Comparable
        DuckWeight weight; //implements Comparable
        String name;
    }
    List&lt;Duck&gt; ducks = Pond.getDucks();

eg. I want to sort them **primarily by their weights**, and **secondarily by their age**. If two ducks have the exact same weight and the exact same age, then let&#39;s differentiate them using their **names as a tertiary key**. I might do something like this:

    Collections.sort(ducks, new Comparator&lt;Duck&gt;(){
        @Override
        public int compare(Duck d1, Duck d2){
            int weightCmp = d1.weight.compareTo(d2.weight);
            if (weightCmp != 0) {
                return weightCmp;
            }
            int ageCmp = d1.age.compareTo(d2.age);
            if (ageCmp != 0) {
                return ageCmp;
            }
            return d1.name.compareTo(d2.name);
        }
    });

Well I do this quite frequently, but this solution doesn&#39;t smell right. It doesn&#39;t scale well, and it&#39;s easy to mess up. Surely there must be a better way of sorting Ducks using multiple keys! Does anybody know of a better solution?

**EDIT** removed unnecessary `else` branches

Sorting Java objects using multiple keys

**Can anyone help me remember what was the flag to tell the XCode to not use ARC for some file?** I had several files in my project marked as such... Until I added another file and decided to convert that one to ARC. Sounds easy, right? I expected that I would be able to simply check a file that I want and let the XCode do it&#39;s magic. Well, not so easy, during pre-check it stripped all -Noarc flags from the files and now I need to manually re- apply the flag to several files. 

the moral of this story is: **once your project is in ARC and you have some files marked as no ARC, do not re-run the convert to ARC tool from Refactor&gt;Convert to ARC.** It will not restore your settings even if pre-check fails. 



ios5 ARC what is the compiler flag to exclude a file from ARC?

Can anyone help me remember what was the flag to tell the XCode to not use ARC for some file? I had several files in my project marked as such... Until I added another file and decided to convert that one to ARC. Sounds easy, right? I expected that I would be able to simply check a file that I want and let the XCode do it's magic. Well, not so easy, during pre-check it stripped all -Noarc flags from the files and now I need to manually re- apply the flag to several files.
the moral of this story is: once your project is in ARC and you have some files marked as no ARC, do not re-run the convert to ARC tool from Refactor>Convert to ARC. It will not restore your settings even if pre-check fails.

While refactoring some code, I came across this strange compile error:

&gt; The constructor call needs to be dynamically dispatched, but cannot be because it is part of a constructor initializer. Consider casting the dynamic arguments.

It seems to occur when trying to call base methods/constructors that take dynamic arguments. For example:

	class ClassA
	{
		public ClassA(dynamic test)
		{
			Console.WriteLine(&quot;ClassA&quot;);
		}
	}

	class ClassB : ClassA
	{
		public ClassB(dynamic test)
			: base(test)
		{
			Console.WriteLine(&quot;ClassB&quot;);
		}
	}

It works if I cast the argument to `object`, like this:

	public ClassB(dynamic test)
		: base((object)test)

So, I&#39;m a little confused. Why do I have to put this nasty cast in - why can&#39;t the compiler figure out what I mean?

Why do I get this compile error trying to call a base constructor/method that takes a dynamic argument?

I&#39;m new to this, and don&#39;t know where to start.

I want to compile a Visual Studio C# project with Mono on Linux (by command line).

The main.cs file includes these references:

    using System;
    using System.IO;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Diagnostics;
    using System.Drawing;
    using System.Drawing.Imaging;
    using System.Net;
    using System.Text;
    using System.Text.RegularExpressions;
    using System.Xml;
    using iTextSharp.text;
    using iTextSharp.text.pdf;

I have no idea whether I need to note the references to the compiler, or whether it will pull them in itself, whether it will know where to look for them or not. I&#39;ve never done this before. But I just need to compile this project.

Thank you!

How to compile a Visual Studio C# Project with Mono

Recently I met the following exception at C# solution:

&gt; Error	2	Could not load file or assembly &#39;Newtonsoft.Json,
&gt; Version=3.5.0.0, Culture=neutral, PublicKeyToken=b9a188c8922137c6&#39; or
&gt; one of its dependencies. The parameter is incorrect. (Exception from
&gt; HRESULT: 0x80070057 (E_INVALIDARG))

		

This does not depend either on my code or on the name of assembly (like `Newtonsoft.Json` in this case).

When I delete this dll from the solution the compiler tells about another in the same exception. So I suppose something shoud be turned off/on at my PC :)

Could not load file or assembly ... The parameter is incorrect

The Java compiler seems to have support for `let` expressions in `com.sun.tools.javac.tree.*` (look for `LetExpr`).

One comment in JCTree even mentions some syntax

    (let int x = 3; in x+2)

which of course is not accepted by the grammar of the language and rejected in an earlier compiler phase.

I&#39;m wondering about the origin of this construct, which I have never seen before.

Is it used internally by `javac` or is it synthesized by other tools? Is it maybe just an artifact from the very early days of Java from a language feature which never saw the light?

Is there anything useful which can be done with it today?

*Generally speaking, why does it exist?*


Purpose of &quot;let expression&quot; (LetExpr) in the Java compiler?

Is there any way or tool to apply GPU acceleration on compiling programs with GCC compiler? Right now I have created a program to compile the given list of programs iteratively. It takes a few minutes. I know of a few programs like Pyrit which helps to apply GPU acceleration for precomputing hashes.

If there are no such tools available, Please advice on whether to use OpenCL or anything else to reprogram my code.

Is it possible to use GPU acceleration on compiling multiple programs on a gcc compiler?

A quick question. 

if I have a property and an ivar declared with the same name:

in the .h file:

    (Reminder*)reminder;
    @property(nonatomic,strong)(Reminder*)reminder;

in the .m file, should I use the ivar or the property in the init method if I&#39;m using ARC?

    - (id)initWithReminder:(Reminder*)reminder_ {
        self = [super init];
        if (self) {
            reminder = reminder_;
        }
        return self;
    }

Or should I use the property to get the benefit of the automatic reference counting like this:

    - (id)initWithReminder:(Reminder*)reminder_ {
        self = [super init];
        if (self) {
            self.reminder = reminder_;
        }
        return self;
    }

I&#39;m not sure at which point in the object&#39;s initialization the properties become accessible with the dot notation.


Should I refer to self.property in the init method with ARC?

ARC forbids Objective-C objects in structs or unions despite marking the file -fno-objc-arc?
Why is this so?

I had the assumption that if you mark it -fno-objc-arc you don&#39;t have this restriction.

ARC forbids Objective-C objects in structs or unions despite marking the file -fno-objc-arc

I have made an application for my client by keeping target iOS as 4.  
But since the application still not submitted to Apple store, my client is planning to upgrade it for iOS 5.0.  

For this I read the [guideline from Apple][1] and found that &quot;Only user-generated data or that cannot otherwise be recreated by your application, should be stored in the &lt;Application_Home&gt;/Documents directory and rest should be stored to &lt;Application_Home&gt;/Library/Caches directory&quot; 

In my application, I am using server model of in-app purchase for non-consumable product. For this I am storing all my downloaded data (which are basically books or magazines) to Documents directory. The Database is also present in the same directory which contains the details about the downloaded products.  

My question is,  
1. Should I have to change my code to store the downloaded data to Library/Caches directory instead of to the Documents directory?  
2. Where should my database file be placed (to Documents or Caches)?  

If I put it products in the Caches then I have to change the logic of retrieval also, since it is considered that if record is present in database, there is no need change the existence of the file and it directly opens it when user clicks on the magazine.  

Kindly guide me on this issue.  
Thanks in advance.

**UPDATED:**  
I am updating this for those who are still not sure about this problem.  
Using the guideline of accepted answer, I have implemented this in 2 of my applications and submitted them to Apple Store. Both were approved in review.  
This may promote that the solution suggested in the accepted answer is correct.  

  [1]: https://developer.apple.com/icloud/documentation/data-storage/

iOS 5 does not allow to store downloaded data in Documents directory?

In iOS 5 I have a Storyboard with a modal view controller, that I would like to display if its the user&#39;s first time in the app, after that I would like to skip this view controller.

I set an NSDefault key to handle this but when I check to see if this is set and then use performSegueWithIdentifier to initiate the segue, nothing happens.  If i put this segue behind a button it works fine...

Perform Segue on ViewDidLoad

On the tech talk 2011 I saw a speech about the new `UIAppearance` [protocol][1].  There is not a lot of documentation out there yet. I will shortly summarize what I remember to explain where my question is coming from:

---
**About `UIAppearance`:**

So far you had to customize EVERY navigation bar (toolbar, etc.) property in all your app view controllers. With the new appearance property you can do it in only one place for all navigation bars in your app. For instance: if you want to customize your Navigation bar background image you could do it like this:

    [[UINavigationBar appearance] setBackgroundImage:
       [UIImage imageNamed:@&quot;MyImageName&quot;] forBarMetrics:UIBarMetricsDefault]; 

This will set the background image of ALL navigation bars within your application. With the `barMetrics` you specify whether you want the image to be used also in landscape mode or not.

If you want to specify the appearance to be applied only in some view controllers there is also a method in the docs to control that by specifying where your objects are located:

    [[UIBarButtonItem appearanceWhenContainedIn:
        [ABPeoplePickerNavigationController class], nil] setTintColor:myNavBarColor];

Also worth to mention is, if you have single customized instances, differing from your appearance settings, theses instances will not be effected by the appearance proxy.  

-----------------------------------------------------------------------------------------
**Some questions:**

**a) How do I know which properties of a class work with the appearance property?** For e.g. since `UITableView` conforms to the UIAppearance protocol I was thinking I could do something like

    [[UITableView appearance] setBackgroundColor:mytableViewColor];

to manipulate the background color of all my table views, but I can&#39;t!  

**b) Is there a list of all classes that are manipulatable with the appearance property?** 

**c) At what point is the appearance customization being called?** I was hoping to make changes threw the appearance property at runtime, but unfortunately the changes aren&#39;t taking place.  


  [1]: https://developer.apple.com/documentation/uikit/uiappearance

iOS 5: Curious about UIAppearance

When creating a project in Xcode 4, it asks what Class prefix to add to all new files.

Is there a way to change (or remove) this, after a project is already started?


How to change the Class Prefix in Xcode 4?

My objective is to create a tabbed application, then the view for each of the tabs are constructed in separate storyboards.

![Storyboard screenshot][1]

My mainstoryboard is a tab view.

Then I create a secondary storyboard (storyboard#2) with 2 View Controllers. The first view controller (also ticked as initial) have a button, and segue (modal) to 2nd view. ![First view controller][2]

I managed to load the view by subclassing and overriding loadView from storyboard#2.
![loadView override][3]

Here&#39;s the simulator output.

![Simulator][4]

When click on the &quot;click me&quot; button, I get a `EXC_BAD_ACCESS`. The segue does not work, seems like the second storyboard is not being loaded completely.

Has anyone tried to do this before and get it working? There&#39;s a youtube video from SkillMaster.net but he does not demonstrate if a segue is working under the secondary storyboard. the video is here: http://youtu.be/D4_twoYvB4M

Thanks for any input and help!

Screenshots:

* http://www.box.com/s/njnyzjoqg8pnqofv838m
* http://www.box.com/s/8dqygclmp5ic86e47bi5
* http://www.box.com/s/k7foe7gpgh2rs3y8gqxd
* http://www.box.com/s/rym111x7xqxqao51ruip

  [1]: http://i.stack.imgur.com/Nw6Zn.png
  [2]: http://i.stack.imgur.com/s848R.png
  [3]: http://i.stack.imgur.com/z7Mgw.png
  [4]: http://i.stack.imgur.com/MvnU6.png

Using Multiple Storyboards in iOS

When view is loaded manually, developer remains in control when it comes to initializations, we choose what initializer to call, what variables to set etc.

When view is loaded from the storyboard segue ... what happens to that initializer? Where should variables be set i&#39;d like to be available once view had been loaded?

Please help me understand the sequence here. How is instance of the class created here, who creates it and how can we intervene and help set it up to our liking?



How is view initialized when loaded via a storyboard?

Is there a way to merge XCode 4.2 Storyboard files? 

I&#39;m working with another developer on an iPhone project and all my attempts at merging changes into a storyboard file have met with failure and after which Xcode is no longer able to load the storyboard. Consequently I have to do an svn revert and then redo my modifications.

XCode Storyboard merging

I am trying to adjust the cell height for one of the cells on my table view. I am adjusting the size from the &quot;row height&quot; setting inside the &quot;size inspector&quot; of the cell in question. When I run the app on my iPhone the cell has the default size set from the &quot;row size&quot; in the table view.

If I change the &quot;row size&quot; of the table view then the size of all cells changes. I do not want to do that as I want a custom size only for one cell. I have seen a lot of posts that have a programmatic solution to the problem, but I would prefer to do it through storyboard, if that is possible.


Custom Cell Row Height setting in storyboard is not responding

Just want to make sure that I got it right:

 1. Do I need to `__unsafe_unretain` objects that I don&#39;t own?
 2. If an object is `__unsafe_unretained` Do I need to use `assign` in the `@property`? Does that mean that the object is not retained, and just refers to the object I assign to?
 3. When would I want to use it except of delegates?
 4. Is that an ARC thing or was it in use before?

ARC - The meaning of __unsafe_unretained?

I&#39;m reading apple&#39;s documentation about &quot;Memory Management for Dispatch Queues&quot;:

&gt; Even if you implement a garbage-collected application, you must still retain and release your dispatch queues and other dispatch objects. Grand Central Dispatch does not support the garbage collection model for reclaiming memory.

I know that ARC is not a garbage collector but I&#39;d like to be sure that I don&#39;t need to dispatch_retain and dispatch_release my dispatch_queue_t

Does ARC support dispatch queues?

I need to generate a UUID string in some code with ARC enabled.

After doing some research, this is what I came up with:

    CFUUIDRef uuid = CFUUIDCreate(NULL);
    NSString *uuidStr = (__bridge_transfer NSString *)CFUUIDCreateString(NULL, uuid);
    CFRelease(uuid);

Am I correctly using `__bridge_transfer` to avoid leaking any objects under ARC?

Content Type	Original Author	Original Content on Stackoverflow
Question	Alex Stone	View Question on Stackoverflow
Solution 1 - Compiler Construction	Alex Stone	View Answer on Stackoverflow
Solution 2 - Compiler Construction	alokard	View Answer on Stackoverflow

ios5 ARC what is the compiler flag to exclude a file from ARC?

Compiler Construction Problem Overview

Compiler Construction Solutions

Solution 1 - Compiler Construction

Solution 2 - Compiler Construction

Sorting Java objects using multiple keys

Usefulness (as in practical applications) of Currying v.s. Partial Application in Scala

Attributions