Standford Cs 193p: 12-text Input Present Modal

CS193P - Lecture 12 iPhone Application Development Text Input Presenting Content Modally

Announcements • Presence 3 assignment out today, due Wednesday 11/5 • Enrolled students can (still) pick up an iPod Touch after class • Final project proposals due on Monday 1/1

Today’s Topics • Notes & Errata • Drawing Optimizations (continued from Tuesday) • iPhone Keyboards • Customizing Text Input • Presenting Content Modally

Notes & Errata

Using UINavigationController • Don’t add a child view controller’s view manually UIViewController *viewController = ...; [navigationController.view addSubview:viewController.view];

• Push a view controller to display it UIViewController *viewController = ...; [navigationController pushViewController:viewController ! animated:YES];

When To Call -init • Call -init (or variants thereof ) only once on an object. Ever. • Seriously.

Operations and Autorelease Pools • If you detach a thread using NSThread, you need to create

your own autorelease pool... • With NSOperation and NSOperationQueue, it’s done for you

Drawing Optimizations (Continued from Tuesday)

Draw Lazily • Never call -drawRect: directly • Invoke -setNeedsDisplay !

Or even better, -setNeedsDisplayInRect:

• In your -drawRect: implementation, only do the work required for the specified rect

Compose with Image Views • When drawing large images on the screen, don’t use a custom

view with an override of -drawRect: • UIImageView has built-in optimizations for speed and memory Memory mapping reduces your footprint ! Doesn’t copy image data to draw !

Avoid Transparency When Possible • Opaque views are much faster to draw than transparent views • Especially important when scrolling • This is the default- introduce transparency with care

Reusing Table View Cells • Memory churn can affect smoothness of scrolling • UITableView provides mechanism for reusing table view cells - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { // Ask the table view if it has a cell we can reuse UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier]; if (!cell) { // If not, create one with our identifier cell = [[UITableViewCell alloc] initWithFrame:CGRectZero identifier:MyIdentifier]; [cell autorelease]; } return cell; }

More on Optimizing Drawing • “iPhone Application Programming Guide - Drawing Tips”

https://developer.apple.com/iphone/library/documentation/ iPhone/Conceptual/iPhoneOSProgrammingGuide/ GraphicsandDrawing/chapter_6_section_3.html

Performance Recap • Performance is both an art and a science !

Combine tools & concrete data with intuition & best practices

• Be frugal with memory • Concurrency is tricky, abstract it if possible • Drawing is expensive, avoid unnecessary work

iPhone Keyboards

Virtual keyboard Appears when needed

Virtual keyboard Appears when needed

Portrait and Landscape

Simple selection model Text loupe/magnifier

Many keyboard types Adapted to task

Many keyboard types Adapted to task

Many keyboard types Adapted to task

Many keyboard types Adapted to task

Many keyboard types Adapted to task

Many keyboard types Adapted to task

Single line editing

Multi-line editing

20 Languages Full dictionary support

English

French

Russian

Korean

Japanese Romaji

Japanese Kana

Chinese Pinyin

Chinese Handwriting Simplified Traditional

Customizing Text Input

Text Containers

Text Containers Delegates Notifications Methods

Text Containers Text Input Traits

Protocol Text Input Traits

UITextField UITextView

Autocapitalization Autocorrection Keyboard Type Text Input Traits

Keyboard Appearance Return Key Type Return Key Autoenabling Secure Text Entry

Text Input Traits

URL Keyboard Go button

Text Input Traits

Default Keyboard Google button

Text Containers Text Input Traits Delegates Notifications Methods

Text Containers

UITextField

Design time

UITextField URL Keyboard Go button

Design time

UITextField URL Keyboard Go button

Run time

UITextField URL Keyboard Go button

Become first responder

Keyboard

UITextField URL Keyboard Go button

Become first responder

Keyboard

UITextField

URL Keyboard Go button

URL Keyboard Go button

Keyboard adopts traits

UITextField Text Containers

UITextView Web Forms

Demo: Text Input

Presenting Content Modally

Presenting Content Modally • For adding or picking data

Presenting // Recipe list view controller - (void)showAddRecipe { RecipeAddViewController *viewController = ...; [self presentModalViewController:viewController animated:YES]; }

Presenting // Recipe list view controller - (void)showAddRecipe { RecipeAddViewController *viewController = ...; [self presentModalViewController:viewController animated:YES]; }

Dismissing // Recipe list view controller - (void)didAddRecipe { [self dismissModalViewControllerAnimated:YES]; }

Dismissing // Recipe list view controller - (void)didAddRecipe { [self dismissModalViewControllerAnimated:YES]; }

Separate Navigation Stacks

Separate Navigation Stacks

Separate Navigation Stacks

Dismissing Modally • Who should do it? • Best practice is for the same object to call present and dismiss • Define delegate methods for the presented controller Tell the delegate when the presented controller is done ! The delegate makes the call to dismiss !

Parent Controller

Present

Child Controller

Dismissing Modally • Who should do it? • Best practice is for the same object to call present and dismiss • Define delegate methods for the presented controller Tell the delegate when the presented controller is done ! The delegate makes the call to dismiss !

Parent Controller I’m done!

Child Controller

Dismissing Modally • Who should do it? • Best practice is for the same object to call present and dismiss • Define delegate methods for the presented controller Tell the delegate when the presented controller is done ! The delegate makes the call to dismiss !

Parent Controller

Dismiss

Child Controller

Presence - Part 3

Goals for Presence 3 • Avoid expensive work on the main thread Use background threads to keep interface responsive ! Abstract thread lifecycle with NSOperation & NSOperationQueue !

• Allow the user to update their own status Text input with the keyboard ! Present a view controller modally !

Demo: Presence 3

Questions?