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191 changes: 90 additions & 101 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -2,19 +2,19 @@

This FAQ originated because I noticed a lot of questions were getting repeated on [/r/iosprogramming](https://reddit.com/r/iosprogramming) so I've decided to write short and sweet answers to all the common questions here. This is a curated list, and I am actively looking for contributions for both questions and answers, so please submit pull requests.

* [Basics](#basics)
* [Prerequisites](#prerequisites)
* [Tools](#tools)
* [SDK](#sdk)
* [Common tasks](#common-tasks)
* [Language](#language)
* [Should I learn Objective-C or Swift first?](#should-i-learn-objective-c-or-swift-first)
* [Cloud and web](#cloud-and-web)
* [Design](#design)
* [Community](#community)
* [Third party code](#third-party-code)
* [The App Store](#the-app-store)
* [Contracting and Employment](#contracting-and-employment)
* Basics
* Prerequisites
* Tools
* SDK
* Common tasks
* Language
* Should I learn Objective-C or Swift first?
* Cloud and web
* Design
* Community
* Third party code
* The App Store
* Contracting and Employment

##Basics

Expand Down Expand Up @@ -141,58 +141,56 @@ Here's a [great list of stats about iOS versions](https://david-smith.org/iosver

You'll need to use [UIAppearance](https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIAppearance_Protocol/):

```objc
//AppDelegate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
UIFont * avenir = [UIFont fontWithName:@"Avenir" size:[UIFont systemFontSize]];
[[UILabel appearance] setFont:avenir];
[[UINavigationBar appearance] setTitleTextAttributes:@{NSFontAttributeName: avenir}];
//You'll need to do this for other classes that display text
return YES;
}
```

// AppDelegate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Override point for customization after application launch.
UIFont * avenir = [UIFont fontWithName:@"Avenir" size:[UIFont systemFontSize]];
[[UILabel appearance] setFont:avenir];
[[UINavigationBar appearance] setTitleTextAttributes:@{NSFontAttributeName: avenir}];
//You'll need to do this for other classes that display text
return YES;
}

###How can I request some JSON from the web?

```objc
//Standard library JSON request to http://httpbin.org

NSURLSession * session = [NSURLSession sharedSession];

//Prepare the request
NSURL * url = [NSURL URLWithString:@"http://httpbin.org/get"];
NSURLRequest * request = [NSURLRequest requestWithURL:url];

//Prepare the data task
NSURLSessionDataTask * dataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
//This block will be executed on the main thread once the data task has completed
//Status Code is HTTP 200 OK
//You have to cast to NSHTTPURLResponse, a subclass of NSURLResponse, to get the status code
if ([(NSHTTPURLResponse*)response statusCode] == 200) {
NSDictionary * json = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
NSLog(@"%@", json);
//The JSON is parsed into standard Cocoa classes such as NSArray, NSDictionary, NSString and NSNumber:
NSLog(@"The requested URL was %@", json[@"url"]);
}
}];

//Begin the task
[dataTask resume];
```
//Standard library JSON request to http://httpbin.org

NSURLSession * session = [NSURLSession sharedSession];

//Prepare the request
NSURL * url = [NSURL URLWithString:@"http://httpbin.org/get"];
NSURLRequest * request = [NSURLRequest requestWithURL:url];

//Prepare the data task
NSURLSessionDataTask * dataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
//This block will be executed on the main thread once the data task has completed
//Status Code is HTTP 200 OK
//You have to cast to NSHTTPURLResponse, a subclass of NSURLResponse, to get the status code
if ([(NSHTTPURLResponse*)response statusCode] == 200) {
NSDictionary * json = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
NSLog(@"%@", json);
//The JSON is parsed into standard Cocoa classes such as NSArray, NSDictionary, NSString and NSNumber:
NSLog(@"The requested URL was %@", json[@"url"]);
}
}];

//Begin the task
[dataTask resume];

`NSURLSession` was introduced in iOS 7 and OS X Mavericks. It provides a reasonably easy way to do concurrent network requests, however you may wish to use [AFNetworking](https://github.com/AFNetworking/AFNetworking) instead as this can reduce the amount of code you have to write:

```objc
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
[manager GET:@"http://httpbin.org/get" parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
//Response object is an NSDictionary, like in the previous example
NSLog(@"JSON: %@", responseObject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
//Handle the error case
NSLog(@"Error: %@", error);
}];
```

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
[manager GET:@"http://httpbin.org/get" parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
// Response object is an NSDictionary, like in the previous example
NSLog(@"JSON: %@", responseObject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
//Handle the error case
NSLog(@"Error: %@", error);
}];


###I want to build a client app for web service X. How do I get started?

Expand Down Expand Up @@ -254,21 +252,19 @@ Objective-C doesn't support namespaces, so all classes are prefixed with the fra

Methods that begin with a `+` are static class methods and are not tied to a particular instance of a class. Class methods are used as:

```objc
//UIView method declaration
+ (void)animateWithDuration:(NSTimeInterval)duration animations:(void(^)(void))animations;
//Is used as:
[UIView animateWithDuration:x animations:^{ /* Animations go here */}];
```

// UIView method declaration
+ (void)animateWithDuration:(NSTimeInterval)duration animations:(void(^)(void))animations;
// Is used as:
[UIView animateWithDuration:x animations:^{ /* Animations go here */}];

Methods that begin with a `-` are instance methods, and are related to a single instance of a class:

```objc
//UIView method declaration:
- (void)addSubview:(UIView*)subview;
//Is used as:
[someViewInstance addSubview:someSubview];
```

// UIView method declaration:
- (void)addSubview:(UIView*)subview;
// Is used as:
[someViewInstance addSubview:someSubview];

The same feature exists in Swift, however the syntax is a little less bizarre. All instance methods just use `func` whereas all static class methods use `class func`.

Expand All @@ -278,43 +274,42 @@ Unlike many other object-oriented programming languages Objective-C has a dynami

Xcode provides a template for extensions, but here is a basic implementation of a map function for `NSArray`:

```objc
//NSArray+FAQ.h

@interface NSArray (FAQ)
// NSArray+FAQ.h

@interface NSArray (FAQ)

/**
@param mapper An Objective-C block which maps objects in the original array to objects in the new array
@return An array of mapped objects
*/
- (NSArray*)faq_map:(id(^)(id))mapper;
/**
@param mapper An Objective-C block which maps objects in the original array to objects in the new array
@return An array of mapped objects
*/
- (NSArray*)faq_map:(id(^)(id))mapper;

@end
@end

//NSArray+FAQ.m
// NSArray+FAQ.m

@implementation NSArray (FAQ)
@implementation NSArray (FAQ)

- (NSArray*)faq_map:(id (^)(id))mapper {
NSMutableArray * array = [NSMutableArray arrayWithCapacity:self.count];
for (id object in self) {
[array addObject:mapper(object)];
- (NSArray*)faq_map:(id (^)(id))mapper {
NSMutableArray * array = [NSMutableArray arrayWithCapacity:self.count];
for (id object in self) {
[array addObject:mapper(object)];
}
return array;
}
return array;
}

@end
@end

//Usage:
//Usage:

#import "NSArray+FAQ.h"
#import "NSArray+FAQ.h"

NSArray * numbers = @[@1, @2, @3, @4];
NSArray * strings = [numbers faq_map:^id(id object) {
return [object stringValue];
}];
NSArray * numbers = @[@1, @2, @3, @4];
NSArray * strings = [numbers faq_map:^id(id object) {
return [object stringValue];
}];

```
Apple recommends that if you are writing your own extension methods that you use three letter prefixes (like with class names) so that you avoid clashing with other methods.

###Can I write an app for the Apple Watch in Objective-C?
Expand Down Expand Up @@ -479,9 +474,3 @@ If there is a copyright issue (i.e. they're purporting to be you, or they've lit
* [Core Inituition Job Board](http://jobs.coreint.org)
* [iOS Dev Weekly](http://iosdevweekly.com) lists jobs listings in its mailing list
* [Stack Overflow Job Board](http://careers.stackoverflow.com/)

**If you've found a job somewhere else that you think should be listed here, pleased add a pull request/issue**

###I have an amazing idea for an app. Where can I hire a developer?

###I've written a great app but I don't do design. Where can I hire a designer?