teaching machines

CS 491 Lecture 11 – Task Navigation

October 8, 2013 by Chris Johnson. Filed under cs491 mobile, fall 2013, lectures.

Agenda

• what ?s
• git client available
• navigating between Activities using intents
• sharing data between Android tasks
• navigating between tasks using UINavigationController
• sharing data between iOS tasks

TODO

• Read up on UINavigationController at  http://www.appcoda.com/use-storyboards-to-build-navigation-controller-and-table-view and https://developer.apple.com/library/ios/documentation/uikit/reference/UINavigationController_Class/Reference/Reference.html. 1/4 sheet.

Sharing Data Between Activities

1. If the data is a message from one Activity to another, use Intent extras. On the sender: intent.putExtra. On the receiver: getIntent().get*Extra(), where * is a primitive type, String, or a few other options. You may need to implement Parcelable for more complex objects. In iOS, you can achieve a similar effect through segues.
2. If the data is truly global and not a message, like a reference to a database, create a singleton. All your code runs in one process, so all Activities will access the same static objects. Alternately, subclass Application and add appropriate instance variables. The Application will need to be pointed to in the manifest. In the Activity, call getApplication() and cast it. In iOS, your AppDelegate can play a similar role.
3. If the data needs to persist between runs of your app, use long-term storage instead.

Code

Memory.h

//
//  Memory.h
//  On Today
//
//  Created by Johnson, Christopher R on 10/3/13.
//  Copyright (c) 2013 Johnson, Christopher R. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Memory : NSObject <NSCopying>
@property (nonatomic, assign, readwrite) int year;
@property (nonatomic, assign, readwrite) int month;
@property (nonatomic, assign, readwrite) int day;
@property (nonatomic, strong, readwrite) NSString *log;
@property (nonatomic, assign, readwrite) int id;

- (id)initWithId:(int)id year:(int)year month:(int)month day:(int)day log:(NSString *)log;
- (NSData *)toJSON;
- (NSString *)dateString;

@end

Memory.m

//
//  Memory.m
//  On Today
//
//  Created by Johnson, Christopher R on 10/3/13.
//  Copyright (c) 2013 Johnson, Christopher R. All rights reserved.
//

#import "Memory.h"

@implementation Memory

@synthesize year = _year;
@synthesize month = _month;
@synthesize day = _day;
@synthesize id = _id;
@synthesize log = _log;

- (id)initWithId:(int)id year:(int)year month:(int)month day:(int)day log:(NSString *)log {
    self = [super init];
    if (self) {
        self.id = id;
        self.year = year;
        self.month = month;
        self.day = day;
        self.log = [log copy];
    }
    return self;
}

- (id)copyWithZone:(NSZone *)zone {
    return [[Memory alloc] initWithId:self.id year:self.year month:self.month day:self.day log:self.log];
}

- (NSString *)description {
    return [NSString stringWithFormat:@"%d - %@", self.year, self.log];
}

- (NSString *)dateString {
    return [NSString stringWithFormat:@"%d/%d/%d", self.year, self.month, self.day];
}

- (NSData *)toJSON {
    NSDictionary *dictionary = [[NSDictionary alloc] initWithObjectsAndKeys:[NSNumber numberWithInt:self.id], @"id", [NSNumber numberWithInt:self.year], @"year", [NSNumber numberWithInt:self.month], @"month", [NSNumber numberWithInt:self.day], @"day", self.log, @"log", nil];
    NSError *error = nil;
    NSData *data = [NSJSONSerialization dataWithJSONObject:dictionary options:0 error:&error];
    return data;
}

@end

ViewController.h

//
//  ViewController.h
//  On Today
//
//  Created by Johnson, Christopher R on 10/3/13.
//  Copyright (c) 2013 Johnson, Christopher R. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController <UITableViewDataSource, UITableViewDelegate>

@end

ViewController.m

//
//  ViewController.m
//  On Today
//
//  Created by Johnson, Christopher R on 10/3/13.
//  Copyright (c) 2013 Johnson, Christopher R. All rights reserved.
//

#import "ViewController.h"
#import "Memory.h"
#import "EditorViewController.h"

@interface ViewController ()
@property (weak, nonatomic, readonly) IBOutlet UITableView *table;
@property (weak, nonatomic, readonly) IBOutlet UIDatePicker *datePicker;
@property (strong, nonatomic, readwrite) NSMutableArray *memories;
@end

typedef struct ymd {
    int year;
    int month;
    int day;
} ymd_t;

@implementation ViewController

@synthesize table = _table;
@synthesize datePicker = _datePicker;

- (void)viewDidLoad {
    [super viewDidLoad];
    self.table.dataSource = self;
    self.table.delegate = self;
    self.memories = [[NSMutableArray alloc] init];
}

- (ymd_t)selectedYMD {
    NSDate *date = self.datePicker.date;
    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    unsigned int flags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit;
    NSDateComponents *components = [calendar components:flags fromDate:date];
    ymd_t ymd = {[components year], [components month], [components day]};
    return ymd;
}

- (IBAction)didDateChange:(UIDatePicker *)picker forEvent:(UIEvent *)event {
    ymd_t ymd = [self selectedYMD];
    [self loadMemoriesForMonth:ymd.month day:ymd.day];
}

- (void)loadMemoriesForMonth:(int)month day:(int)day {
    dispatch_queue_t q = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0L);
    
    dispatch_async(q, ^{
        NSDictionary *dictionary = [[NSDictionary alloc] initWithObjectsAndKeys:[NSNumber numberWithUnsignedInt:month], @"month", [NSNumber numberWithUnsignedInt:day], @"day", nil];
        NSError *error;
        NSData *data = [NSJSONSerialization dataWithJSONObject:dictionary options:0 error:&error];
        NSDictionary *result = [self makeRequest:@"http://www.twodee.org/ontoday/get.php" json:data];
        
        dispatch_sync(dispatch_get_main_queue(), ^{
            [self.memories removeAllObjects];
            NSArray *memoriesArray = [result objectForKey:@"memories"];
            for (NSDictionary *md in memoriesArray) {
                NSLog(@"%@", md);
                Memory *memory = [[Memory alloc] initWithId:[[md objectForKey:@"id"] intValue] year:[[md objectForKey:@"year"] intValue] month:[[md objectForKey:@"month"] intValue] day:[[md objectForKey:@"day"] intValue] log:[md objectForKey:@"log"]];
                [self.memories addObject:memory];
            }
            [self.table reloadData];
        });
    });
}

- (NSDictionary *)makeRequest:(NSString *)urlString json:(NSData *)json {
    NSURL *url = [NSURL URLWithString:urlString];
    
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    [request setHTTPMethod:@"POST"];
    [request setHTTPBody:json];
    [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
    [request setValue:[NSString stringWithFormat:@"%d", [json length]] forHTTPHeaderField:@"Content-Length"];
    
    NSError *error = nil;
    NSURLResponse *response = [[NSURLResponse alloc] init];
    NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];

    NSDictionary *result = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];
    return result;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return [self.memories count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];
    if (!cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cell"];
    }
    
    cell.textLabel.text = [[self.memories objectAtIndex:[indexPath row]] description];
    
    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    [self performSegueWithIdentifier:@"toEdit" sender:self];
}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    EditorViewController *target = segue.destinationViewController;
    
    if ([segue.identifier isEqualToString:@"toAdd"]) {
        ymd_t ymd = [self selectedYMD];
        Memory *m = [[Memory alloc] initWithId:-1 year:ymd.year month:ymd.month day:ymd.day log:@""];
        target.memory = m;
    } else if ([segue.identifier isEqualToString:@"toEdit"]) {
        Memory *m = [self.memories objectAtIndex:[[self.table indexPathForSelectedRow] row]];
        target.memory = m;
    }
}

@end

EditorViewController.h

//
//  EditorViewController.h
//  On Today
//
//  Created by Johnson, Christopher R on 10/3/13.
//  Copyright (c) 2013 Johnson, Christopher R. All rights reserved.
//

#import <UIKit/UIKit.h>

#import "Memory.h"

@interface EditorViewController : UIViewController
@property (strong, nonatomic, readwrite) Memory *memory;
@end

EditorViewController.m

//
//  EditorViewController.m
//  On Today
//
//  Created by Johnson, Christopher R on 10/3/13.
//  Copyright (c) 2013 Johnson, Christopher R. All rights reserved.
//

#import "EditorViewController.h"

@interface EditorViewController ()
@property (weak, nonatomic, readwrite) IBOutlet UITextView *logEditor;
@end

@implementation EditorViewController

@synthesize memory = _memory;
@synthesize logEditor = _logEditor;

- (void)viewDidLoad {
    self.logEditor.text = [self.memory log];
}

- (void)setMemory:(Memory *)memory {
    _memory = memory;
    self.logEditor.text = _memory.log;
}

@end

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