Post WDI - iOS Development App (Master-Detail Table View, JSON, API, Mutable, Memory Management)

Activities @ TeamTreeHouse - 

iOS Development (using Xcode 5 IDE) with Amit Bijlani (Cont'd)

DONE Building API Reader (Table View) iPhone App

• Table View (List) with Master-Detail App
• Manual
• Master-Detail Template
• UIApplication { single instance, only allowed one UIApplication object for a single app. watches for Events and Routes to appropriate targets }
• AppDelegate
• Dfn: capability to Intercept Events at an App level so can Add Custom code. all apps have it to hook into UIApplication (app lifecycle). responsible to ensure app has a Window 
• .h { defines lifecycle of app }
• .m { implementation of .h containing methods }
• UIWindow object { coordinates presentation of Views on screen. hosting Views and working with UIApplication object to deliver Events to Views and View Controller }
• View Controller object { manages presentation of app Content on screen, including Single MainView (property) and its Collection of Sub Views  i.e. self.view (where View is property of ViewController) }
• UIViewController class { base class for all ViewController objects, provides Default functionality for Views' ability to load, display, respond, etc }
• View object { draws Content in designated Rect area and Responds to Events in that area }
• Controls { specialised Views responsible for implementing interface objects (i.e. buttons, text fields, toggle switches) }
• Data { ways to store data in app (i.e. Core Data, etc) }
• Storyboard (defines flow between ViewControllers)
• MasterViewController { inherits from UITableViewController and UIViewController as displays List of TableView UITableView with Rows(UITableViewCells) attributes and behaviour and where tap event shows DetailViewController }
• DetailViewController  { inherits from UIViewController as displays Single View Text from Table View Cell }
• Scene { ViewControllers }
• Segue {  connection between Scenes of type UIStoryboardSegue (arrow Transition between each View Controller). it has Properties: identifier, sourceViewController, destinationViewController }
• identifier { read-only shown in View. accessed in code with method prepareForSegue. use Method notation (instead of Dot Notation) when dealing with 'read-only' info as indicated in Help }
• prepareForSegue { intercepts Segue once it is triggered and takes two args }
• Segue param { contains info about Segue }
• sender { originator of Segue }

(UIStoryboardSegue *)segue sender:(id)sender

• Shortcuts
• Double-Click - Zoom in/out of Storyboard canvas 
• CMD+N - New File
• UITableViewController { is declared in NSObjCRuntime.h (according to hover+CMD+Click) and implements two Protocols. It contains a @property 'tableView' of type UITableView which implements the two Protocols }
• UITableViewDataSource { defines what is displayed in Table View. it mediates between Table View and Data }
• UITableViewDelegate { defines how Data displayed with Methods to configure Table Views (i.e. row heights, section headers/footers, tap event or editing actions) }

@property (nonatomic, retain) UITableView *tableView;

• indexPath { object with two Properties (Section, and Row in that Section) }
• Memory Management
• No Table View Cell Reuse { alloc and init new table view cell for each row to be displayed in table view. slow with large quantities of rows in the array to be alloc'ed }

UITableViewCell *cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"Cell"];

• Efficient Reuse of Table View Cells { allows table view to efficiently manage cells with each one having an identifier in storyboard so when table view cell scrolls beyond screen the table view re-marks it for reuse and recycles it on new row }

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];

• NSDictionary 
• objectForKey { type 'id' is generic data type (any Object) }
• valueForKey { always expects String }

// declaration for key value pair NSDictionary *blogPost1 = [[NSDictionary alloc] initWithObjectsAndKeys:@"Blogpost1", @"title", @"Luke Schoen", @"author", nil]; 
// ALTERNATIVE convenience constructor for NSDictionary NSDictionary *blogPost1 = [NSDictionary dictionaryWithObjectsAndKeys:@"Blogpost1", @"title",@"Luke Schoen", @"author", nil];

• SubTitles { Storyboard > Change Type (of TableViewCell) in Attribute Inspector > subTitle }
• UITableViewCell Properties:
• textLabel
• detailTextLabel
• Mutable 
• Memory Inefficency { performance overhead when want to modify Contents of object, mem alloc needs to change and find mem space for additional Content }
• NSMutableArray (subclass of NSArray)

NSMutableArray *titles = [NSMutableArray arrayWithCapacity:0]; // if capacity 0, use below NSMutableArray *titles = [NSMutableArray array]; // memory alloc minimal to hold pointer to array [titles addObject:@“My Book”]; // add object to array. mem dynamically alloc. array size grows [titles insertObject:@“abc” atIndex:0];  [titles removeLastObject]; [titles removeObjectAtIndex:0]; 

• NSMutableDictionary (subclass of NSDictionary)
• Declare with Memory Capacity

NSMutableDictionary *book = [NSMutableDictionary dictionary]; [book setObject:@“My Book”, forKey:@”title”]; [book setObject:@“Luke Schoen”, forKey:@”author"]; [book removeObjectForKey:@“title”]; [book removeAllObjects]; // removes all objects from a dictionary

• NSMutableString (subclass of NSString) 

NSMutableString *string = [NSMutableString string];[string appendString:@"Title: My Book"];[string appendString:@"Author: Luke Schoen"];[string insertString:@" -- " atIndex:10]; 

• Immutable { cannot be modified } 
• Memory Efficient { when variable for object alloc, mem req'd known (knows qty objects and kind of objects. pass around without need to modify }
• NSArray
• JSON Parsing (JavaScript Object Notation)

// create NSURL class object (convenience class to breakdown url) 

// download the data (NSData object stream from JSON)   

NSURL *movieURL = [NSURL URLWithString:@"http://www.omdbapi.com/?s=Terminator"]; 

// parse data  

NSData *jsonData = [NSData dataWithContentsOfURL:blogURL]; 

// declare pointer in memory 

NSError *error = nil; 

// deserialise data into JSON object format to stored in dictionary 

// pass pointer reference to NSError so value can be modified by the method it is being passed to (otherwise just passing by value and can only read 

// i.e. &__ means value can be modified by the method 

// i.e. ___ means just passing its value and it can only read your object NSDictionary *dataDictionary = [NSJSONSerialization JSONObjectWithData:jsonData options:0 error:&error]; NSLog(@"%@", dataDictionary);
self.moviePosts = [dataDictionary objectForKey:@"Search”];

// extract 'title' from NSDictionary and set

cell.textLabel.text = [moviePost valueForKey:@"Title"];
cell.detailTextLabel.text = [moviePost valueForKey:@"Year"];

Events Upcoming

• ATTENDED - RORO Syd Dev Hub - 6:30pm 6th May 2014 (Level 15, 2 Market St)
• UNABLE - RORO USer Group - 7pm 13th May 2014 (Trinity Bar, 505 Crown St Surry Hills)
• UNABLE - Sydney Drupal Meetup - 7pm, 15th May 2014 (Level 5, 48 Pirrama Rd)