TWViewController.m

//
//    TWViewController.m
//    TWiOSReverseAuthExample
//
//    Copyright (c) 2013 Sean Cook
//
//    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.
//

#import <Accounts/Accounts.h>
#import <Twitter/Twitter.h>
#import "OAuth+Additions.h"
#import "TWAPIManager.h"
#import "TWSignedRequest.h"
#import "TWViewController.h"

#define ERROR_TITLE_MSG @"Whoa, there cowboy"
#define ERROR_PERM_ACCESS @"We weren't granted access to the user's accounts"
#define ERROR_NO_KEYS @"You need to add your Twitter app keys to Info.plist to use this demo.\nPlease see README.md for more info."
#define ERROR_OK @"OK"

@interface TWViewController()

@property (nonatomic, strong) ACAccountStore *accountStore;
@property (nonatomic, strong) TWAPIManager *apiManager;
@property (nonatomic, strong) NSArray *accounts;
@property (nonatomic, strong) UIButton *reverseAuthBtn;

@end

@implementation TWViewController

#pragma mark - UIViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nil bundle:nil];
    if (self) {
        _accountStore = [[ACAccountStore alloc] init];
        _apiManager = [[TWAPIManager alloc] init];
    }
    return self;
}

- (void)loadView
{
    CGRect appFrame = [UIScreen mainScreen].applicationFrame;

    CGRect buttonFrame = appFrame;
    buttonFrame.origin.y = floorf(0.75f * appFrame.size.height);
    buttonFrame.size.height = 44.0f;
    buttonFrame = CGRectInset(buttonFrame, 20, 0);

    UIView *view = [[UIView alloc] initWithFrame:appFrame];
    [view setBackgroundColor:[UIColor colorWithWhite:0.502 alpha:1.000]];

    UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"twitter.png"]];
    [view addSubview:imageView];
    [imageView sizeToFit];
    imageView.center = view.center;

    CGRect imageFrame = imageView.frame;
    imageFrame.origin.y = floorf(0.25f * appFrame.size.height);
    imageView.frame = imageFrame;

    _reverseAuthBtn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [_reverseAuthBtn setTitle:@"Perform Token Exchange" forState:UIControlStateNormal];
    [_reverseAuthBtn addTarget:self action:@selector(performReverseAuth:) forControlEvents:UIControlEventTouchUpInside];
    _reverseAuthBtn.frame = buttonFrame;
    _reverseAuthBtn.enabled = NO;
    [_reverseAuthBtn setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    [view addSubview:_reverseAuthBtn];

    self.view = view;
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    [self refreshTwitterAccounts];
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(refreshTwitterAccounts) name:ACAccountStoreDidChangeNotification object:nil];
}

- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

#pragma mark - UIActionSheetDelegate

- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if (buttonIndex != actionSheet.cancelButtonIndex) {
        [_apiManager performReverseAuthForAccount:_accounts[buttonIndex] withHandler:^(NSData *responseData, NSError *error) {
            if (responseData) {
                NSString *responseStr = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];

                TWDLog(@"Reverse Auth process returned: %@", responseStr);

                NSArray *parts = [responseStr componentsSeparatedByString:@"&"];
                NSString *lined = [parts componentsJoinedByString:@"\n"];

                dispatch_async(dispatch_get_main_queue(), ^{
                    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Success!" message:lined delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
                    [alert show];
                });
            }
            else {
                TWALog(@"Reverse Auth process failed. Error returned was: %@\n", [error localizedDescription]);
            }
        }];
    }
}

#pragma mark - Private
/**
 *  Checks for the current Twitter configuration on the device / simulator.
 *
 *  First, we check to make sure that we've got keys to work with inside Info.plist (see README)
 *
 *  Then we check to see if the device has accounts available via +[TWAPIManager isLocalTwitterAccountAvailable].
 *
 *  Next, we ask the user for permission to access his/her accounts.
 *
 *  Upon completion, the button to continue will be displayed, or the user will be presented with a status message.
 */
- (void)refreshTwitterAccounts
{
    TWDLog(@"Refreshing Twitter Accounts \n");

    if (![TWAPIManager hasAppKeys]) {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:ERROR_TITLE_MSG message:ERROR_NO_KEYS delegate:nil cancelButtonTitle:ERROR_OK otherButtonTitles:nil];
        [alert show];
    }
    else if (![TWAPIManager isLocalTwitterAccountAvailable]) {
        TWTweetComposeViewController *tweetView = [[TWTweetComposeViewController alloc] init];
        tweetView.view.hidden = YES;
        tweetView.completionHandler = ^(TWTweetComposeViewControllerResult result) {
            [self dismissModalViewControllerAnimated:NO];
        };
        [self presentModalViewController:tweetView animated:NO];
        [tweetView.view endEditing:YES];
    }
    else {
        [self obtainAccessToAccountsWithBlock:^(BOOL granted) {
            dispatch_async(dispatch_get_main_queue(), ^{
                if (granted) {
                    _reverseAuthBtn.enabled = YES;
                }
                else {
                    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:ERROR_TITLE_MSG message:ERROR_PERM_ACCESS delegate:nil cancelButtonTitle:ERROR_OK otherButtonTitles:nil];
                    [alert show];
                    TWALog(@"You were not granted access to the Twitter accounts.");
                }
            });
        }];
    }
}

- (void)obtainAccessToAccountsWithBlock:(void (^)(BOOL))block
{
    ACAccountType *twitterType = [_accountStore accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];

    ACAccountStoreRequestAccessCompletionHandler handler = ^(BOOL granted, NSError *error) {
        if (granted) {
            self.accounts = [_accountStore accountsWithAccountType:twitterType];
        }

        block(granted);
    };

    //  This method changed in iOS6. If the new version isn't available, fall back to the original (which means that we're running on iOS5+).
    if ([_accountStore respondsToSelector:@selector(requestAccessToAccountsWithType:options:completion:)]) {
        [_accountStore requestAccessToAccountsWithType:twitterType options:nil completion:handler];
    }
    else {
        [_accountStore requestAccessToAccountsWithType:twitterType withCompletionHandler:handler];
    }
}

/**
 *  Handles the button press that initiates the token exchange.
 *
 *  We check the current configuration inside -[UIViewController viewDidAppear].
 */
- (void)performReverseAuth:(id)sender
{
    UIActionSheet *sheet = [[UIActionSheet alloc] initWithTitle:@"Choose an Account" delegate:self cancelButtonTitle:nil destructiveButtonTitle:nil otherButtonTitles:nil];
    for (ACAccount *acct in _accounts) {
        [sheet addButtonWithTitle:acct.username];
    }
    sheet.cancelButtonIndex = [sheet addButtonWithTitle:@"Cancel"];
    [sheet showInView:self.view];
}

@end