1 / 37

Wednesday 2-4, DH 1046

Wednesday 2-4, DH 1046. COMP 446 / ELEC 446 Mobile Device Applications. Scott Cutler Professor in the Practice of Computer Technology Department of Computer Science Department of Electrical and Computer Engineering cutler@rice.edu 9/14/11. Today’s Agenda. Events of the week

chad
Download Presentation

Wednesday 2-4, DH 1046

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Wednesday 2-4, DH 1046 • COMP 446 / ELEC 446 • Mobile Device Applications Scott Cutler Professor in the Practice of Computer Technology Department of Computer Science Department of Electrical and Computer Engineering cutler@rice.edu 9/14/11

  2. Today’s Agenda • Events of the week • Final Project Philosophy • Review of current assignment • Memory Management • Next Week • Views, drawing, application life cycle • Assignment 3, Videos 5 and 6 • Graphing version of this week’s calculator COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 2

  3. Events of the Week • Google: Mobile devices to generate 15% of Black Friday searches • Google buys Zagat, in original-content gambit • Google to debut Dart, a new language for the Web • Best Buy Adds RIM's Playbook To Heap Of El Cheapo Non-iPads • Windows Phone Marketplace boots AVG app • Windows 8 unveiled • Nvidia launches Windows 8 developer program • Nvidia Readies Quad-Core Tegra Chips for Mobile Devices • Apple iPads, iPhones get Flash video at last (not really) • Flash-derived iPad game tops App Store charts • AMD's FX CPU hits record-breaking speeds • Microsoft to update the Xbox 360's user interface • HTC interested in buying its own mobile OS • How HTML5 may become the standard for apps • Intel and Google to partner on next-gen Android devices COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 3

  4. Assignment Mulligan • Large percentage of assignments late. • Issues with every submission • Difficult but very fundamental topic • Time for your one and only Mulligan COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 4

  5. Assignment Planning • Much of this material is confusing until understood. • Assignments meant to pace you through major elements • Weekly video 1 introduces concepts. Video 2 demonstrates concepts required by homework. • Very difficult to get homework done without watching videos. • Expect something not to work as expected! COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 5

  6. Anticipating Issues • Actual coding of assignment may take less than an hour if you are an expert; however . . . • Understanding what is wanted and how to approach takes time • iOS can be very confusing at the beginning • Bugs often obscure, manifesting themselves in places no where near the problem • Can easily get stumped for hours • Starting the assignment near the end is highly risky. • You will not get another Mulligan COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 6

  7. COMP 446 Syllabus • 8/24/11Introduction / What makes mobile apps special Videos: Lecture 1. Introduction to Cocoa Touch, Objective-C, Tools, and MVC (September 21, 2010) Lecture 2. Building a Simple Calculator (September 23, 2010) Assignment: #1 and #1 Walkthrough - Calculator Due: Preferably watch videos this week, definitely by 8/30. Assignment due 9/1/11. • 8/31/11Discussion of first applications, Development Environment Videos: Lecture 3. Objective-C and Foundation Frameworks (September 28, 2010) Lecture 4. Foundation and Memory Management (September 30, 2010) Assignment: #2 Function Calculator (Due 9/15/11) • 9/7/11 Intro to Cocoa Touch, Objective-C, Using Objective-C, Foundation framework Videos: Assignment: • 9/14/11Memory Management Videos: Lecture 5. Protocols and Views (October 5, 2010) Lecture 6. Application & View Controller Lifecycle, Navigation Controller (October 7, 2010) Assignment: #3 Graphing Calculator (Due 9/22/11) • 9/21/11iPhone (pseudo) Web Apps / ASP.Net / Browser Capabilities Videos: Lecture 7. More Controllers of Controllers, iPad, Universal Applications (October 12, 2010) Lecture 8. Gesture Recognizers (October 14, 2010) Assignment: #4 Universal Calculator (Due 9/29/11) COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 7

  8. COMP 446 Syllabus • 9/28/11SQL 101 Videos: Lecture 9. Image View, Web View, and Scroll View (October 19, 2010) Lecture 10. Table View (October 21, 2010) Assignment: #5 Pictures Places (Due 10/13/11) • 10/5/11Creating and Consuming Web Services Videos: Lecture 11. Persistence (October 26, 2010) Lecture 12. Core Data and Table Views (October 28, 2010) Assignment: #6 Core Data Places (Due 10/20/11, but watch lectures prior to 10/12/11 class) • 10/12/11Final Project discussion and Pairing Videos: Debugging Tools (October 22, 2010) Kleiner Perkins iFund (October 15, 2010) Assignment: Final Project Proposal (Due 10/18/11 along with Core Data Places due 10/20/11) • 10/19/11iOS 5 Videos: Lecture 13. Blocks and Multithreading (November 2, 2010) Lecture 14. Core Location and Map Kit (November 9, 2010) Assignment: Final Project, Stage 1 (Due 10/27/11) • 10/26/11Android Videos: Lecture 15. Editable Text, Modal View Controllers, and View Animation (Nov 11, 2010) Lecture 16. Core Motion, Segmented Control, and Alerts (November 16, 2010) Assignment: Advanced Feature App (Due 11/03/11) COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 8

  9. COMP 446 Syllabus • 11/2/11Windows Phone 7, Final Project Prep Videos: Lecture 17. Media (November 18, 2010) Lecture 18. Accessibility on iOS: Make an App for Everyone (November 30, 2010) Assignment: Final Project, Stage 2 (Due 11/10/2011) • 11/09/11Final Project Prep / iPhone v. Android v. Windows Phone 7 group discussion Videos: Lessons from Bezos, Pincus, Young: CEO 2.0 (November 12, 2010) (Optional) LinkedIn: Shipping with CoreData (November 5, 2010) (Optional) Assignment: Final Project, Stage 3 (Due 11/17/2011) • 11/16/11Final Project Prep Videos: Building Flipboard (November 19, 2010) (Optional) Assignment: Final Project Presentation (Due 11/30/2011) • 11/23/11Thanksgiving – Continue Final Projects on your own • 11/30/11Demonstrate Final Projects to class • 12/4/11Class Offsite – Sunday (tentative) • FinalsSubmission of final code due by official finals date COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 9

  10. Final Project • To be determined by end of 6th week • Can target iOS, Android or WP7 device • Topic chosen class before mid semester break • Proposal submitted by 10/18/11 • Full Spec 10/27/11 • Various milestones including presentation to class on 12/30/11 • Final code for project incorporating comments from presentation due on the official finals date of the course. • This is VERY important: If you do not have a great project definition, the 2nd half of the course will suffer. With a great project, this will be an exciting course. • Projects can be done solo and in pairs. Richard Latimer can not be part of project team. • Great if your project could have life after the class finishes COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 10

  11. Week 5 • Watch CS193p lectures #5 and #6 • Preferably before Saturday. Definitely before next class. • Complete CS193p Assignment #3 • Try and complete before next class. Due day after next class. • Submit assignments, review lectures at www.comp446.com • Start thinking about big project COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 11

  12. Memory Management COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 12

  13. Memory Management Basics • Object Creation • + alloc and - init methods • Objects take space, space allocated with alloc and initialized with init. • Objects kept alive via a retention count. • [object retain] increases that count by 1 • [object release] decrease that count by 1 • When count reaches 0, [object dealloc] automatically called. • Objects retained by other objects need to be released when finished • Either when explicitly finished or in the dealloc method • Objects which might get released to 0 by others need to be retained COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 13

  14. Pointers vs. Objects • Objects exist in the heap and take up resources • Variable names, for example (NSString *) point at objects. Their value is a pointer to the actual object. • Names can be set to nil (0) when they point to nothing • C values (e.g double, int) are stored with class instance and do not have to be managed COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 14

  15. Pointers vs. Objects • Copying objects, particularly NSString guarantees they won’t be changed from under you • You may cast them as an NSString, but it might be an NSMutableString • Multiple names can point to the same object • (NSMutableString *)mstring1 = [NSMutableString setString:@”Hi”];(NSString *)string2 = mstring1; // string2 == mstring1; both point to same object COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 15

  16. Instance Variables and Properties Memory • Instance variables take up some space • int, float, etc store the actual values • (NSString *) iVar saves room for a pointer to an NSString object • The space needed by the actual object goes away when the object is deallocated, not when the pointer goes away. • Variables initialized to 0 or nil. This includes pointer objects. • Instance variables assigned to objects need to be released during [object dealloc] • OK to message nil objects, notOK to release deallocated objects COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 16

  17. Example: NSString Setter (retain) • - (void)setName:(NSString *)newName { if (name != newName) { [name release]; //old name retain count down 1 name = [newName retain]; // name’s retain count has been bumped up by 1} COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 17

  18. Example: NSString Setter (copy) • - (void)setName:(NSString *)newName { if (name != newName) { [name release]; //old name retain count down 1 name = [newName copy]; // name has retain count of 1, we own it} COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 18

  19. Which @property attribute to use • @property (retain) id expression; • Use retain for most objects. • Setter will properly release previous value and retain new value • @property (copy) NSString *aString; • Use for any object where the underlying object might change. • Often done for NSString as it might be owned by someone else as an NSMutableString. • You may want to use it for NSArray, NSDictionary, NSSet • @property (assign) UITableViewDelegate *myDelegate; • Primarily used for objects which don’t go away; specifically delegates. COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 19

  20. Property Memory Management • Header options • readonly – getter, no setter. Property can not be changed. • readwrite (default) – setter and getter • assign, retain and copy relate to how setter is coded assign retain copy • (void)setName: (NSString *)value • { • if (value != name) { • // [name release]; • name = value; • } • } // Probably you would not want this • (void)setName: (NSString *)value • { • if (value != name) { • [name release]; • name = [value retain]; • } • } //Name points to other object • (void)setName: (NSString *)value • { • if (value != name) { • [name release]; • name = [value copy]; • } • } // Creates a copy which you own COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11

  21. Autorelease • If you know you are finished with an object and you retained or own it, release it when finished. It will go away if you are the last reference. • If you no longer need the object yourself, but want to pass it to someone else, autorelease the object; let them be responsible for retaining it. • If you know you will be done with the object during this run loop but can’t tell where in your code you may finish with it, autorelease the object. • If you acquire an autoreleased object and believe you will need it on a different run-loop cycle, retain the object and later release it. • Do not sprinkle autoreleases. They should be deliberate. COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 21

  22. Initial Retention Count • Objects received through [[class alloc] init] or [class copy] come with a retention count of 1 • By convention, all other objects are owned by others and likely come autoreleased • They will be automatically destroyed on next wait loop unless otherwise retained • If you create and own an object in a method whose name does not start with new, init or copy, make sure you autorelease it before returning COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 22

  23. - (void) dealloc { } • First (optional step) is to run any logic cleanup code • Second step is to release any retained objects. • [object release], not [object deallocate]. • Do not release the deallocated object itself (no [self release]) • Final step is to call [super dealloc] COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 23

  24. What to release in dealloc • All of your iVars • This includes all IBOutlets • Any other retained objects • Better practice is to release or autorelease non-iVar objects closer to where they are being used after finishing with them. COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 24

  25. Use Your @properties • Release your IBOutlets by setting them to nil. • Do not use myOutlet = nil; as that will likely leak memory. • Use self.myOutlet = nil; • Why not to use [myOutlet release]; • Still leaves myOutlet pointing to a likely destroyed object. • Releasing a destroyed object raises an error • Releasing a nil object is fine COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 25

  26. Application Life Cycle Events • You will soon learn about • viewDidLoad • viewDidUnload • Application:didFinishLaunchingWithOptions: • awakeFromNib • etc • You will want to release IBOutlets in viewDidUnload and dealloc. • Put set of “self.myOutlet=nil” statements in private method • Call method from viewDidUnload and dealloc. • Remember no problem sending messages to nil • Cannot release a destroyed object COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 26

  27. Common Problems • NSMutableArray *mutableArray; • [mutableArray addObject:anObject]; COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 27

  28. Common Problems • Foo.h Foo.m • @interface { • double waitingOperand; • NSString *waitingOperation; • NSArray *expression; • } • -(void) dealloc { • [waitingOperand dealloc]; • [NSArray dealloc]; • [super dealloc]; • } COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11

  29. Common Problems • Foo.h Foo.m • @interface { • double waitingOperand; • NSString *waitingOperation; • NSArray *expression; • } • -(void) dealloc { • [waitingOperand release]; • [NSArray release]; • [super release]; • } COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11

  30. Common Problems • - (NSArray *) expressionArray:(NSMutableArray *)expression { • NSArray *result = [expression copy]; • return result; • } COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 30

  31. Common Problems • - (viewDidLoad){ • CalculatorBrain *brain=[[CalculatorBrain alloc] init]; • return brain; • } COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 31

  32. Common Problems • - (viewDidUnload){ • display=nil; • } COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 32

  33. NSZombieEnabled • Product Edit Scheme Arguments tab • Under Environment Variables, add • NSZombieEnabled with value YES • You will be notified when you try to use an object which has been deallocated. COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 33

  34. Assignment #2 Common Problems • Not releasing all iVars in dealloc • On extra credit, setting myOutlet=nil rather than self.myOutlet=nil • Using unallocated or initialized variables • NSMutableString *aMutableString; does not allocate it. It may reserve space for the pointer, but nothing has yet been created. • Using nondescriptive iVar names • OK to use aString inside method, but not as iVar • Releasing iVars other than IBOutlets in viewDidUnload COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 34

  35. Assignment #2 Common Problems • Doing nothing with property list functions • Don’t try to game assignment. Some things are there purely for pedagogical value. • Code that crashed (OK if you tell me it is a work in progress) • Not using all possible appropriate properties • Deallocing objects rather than releasing them • Returning a non-autoreleased object from a method that does not start with init, copy or new. • Confusing names. Use aSet rather than set. COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 35

  36. Calculator View Controller COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 36

  37. Calculator Brain COMP 446 / ELEC 446 - Week 4 SEC - 9/14/11 37

More Related