Intro to iOS Development Patrick Linskey @plinskey You - - PowerPoint PPT Presentation

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Intro to iOS Development Patrick Linskey @plinskey You - - PowerPoint PPT Presentation

Oct 06, 2022 155 likes •657 views

Intro to iOS Development Patrick Linskey @plinskey You Enterprise Java iOS development Me Patrick Linskey @plinskey http://versly.com Objective C Primer Object-oriented extension of C Smalltalk-like syntax Full C

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Intro to iOS Development

Patrick Linskey @plinskey

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You

Enterprise Java iOS development

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Me

Patrick Linskey @plinskey http://versly.com

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Objective C Primer

  • Object-oriented extension of C
  • Smalltalk-like syntax
  • “Full” C compatibility
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[object message]

  • Messages, not methods
  • Braces at the beginning, which is weird.

id list = [[NSArray alloc] init];

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Message Arguments

id text = [NSString stringWithFormat:@“Hello, %@!”, @“Copenhagen”];

  • Arguments are embedded in the message signature
  • Akin to named parameters, but order is fixed
  • Type overloading is unsupported
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Legacy C issues

  • Header files
  • Single-pass compilation
  • Forward-declare private messages, or

careful class file definition ordering

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@ Directives

  • Objective C preprocessor directives
  • Strings: @“foo”
  • Properties: @property, @synthesize
  • Multi-threading: @synchronized
  • etc.
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Architecture

JEE

JSP JSP JSP Servlet JAX JAX JAX EJB EJB EJB Logic Entity Store

Presentation Business Integration

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Architecture

iOS

Logic Entity Store EIS Widget View

Model View Controller

View Controller

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Model View Controller

M V C

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View

V

Root View Image View Control View Play Button Pause Button Tree

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V

Layout

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int height = view.height; int height = [view height]; int width = view.width; int width = [view width];

C

int width = view.getWidth(); int height = view.getHeight(); view.setSize(10, 20); [view setWidth:10 height:20]; ObjC Syntax

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Listeners vs Actions

C

button.setOnClickListener(new OnClickListener() { @Override public void onClick(Event e) { doSomething(); } }); [button addTarget:self action:@selector(doSomething) forControlEvents:TouchUpInside];

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C

Notifications

Notification Center Sender Observer

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Notifications

C

[[NotificationCenter defaultCenter] postNotificationName:PersonDidDeleteNotification

  • bject:person];

. . . [[NotificationCenter defaultCenter] addObserver:self selector:@selector(personDidDelete:) name:PersonDidDeleteNotification

  • bject:nil];

. . .

  • (void)personDidDelete:(Notification*)notification {

Person *person = [notification object]; ... }

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Delegates

C

@protocol ListViewDelegate

  • (int)numberOfItemsInListView:(ListView*)list;
  • (ListItem*)listView:(ListView*)list itemAtIndex:(int)i;

... @optional

  • (void)listView:(ListView*)list didSelectItemAtIndex:(int)i;

... @end

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Concurrency

Any sufficiently advanced bug is indistinguishable from a feature.

  • Bruce Brown
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Concurrency

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Concurrency

JEE

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Concurrency

iOS

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Data *data = ...; id result = [self processData:data]; [view display:result]; [view show]; Data *data = ...; [self performSelectorInBackground:@selector(processData:) withObject:data]; . . .

Concurrency

iOS

  • (void)processData:(Data*)data {

id result = ...; [self performSelectorOnMainThread:@selector(display:) withObject:result waitUntilDone:NO]; }

  • (void)display:(id)result {

[view display:result]; [view show]; }

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[self performSelector:@selector(hideControls) withObject:nil afterDelay:3.0]; . . .

[busyIndicator show]; [self processData:data];

Concurrency

iOS

[Object cancelPreviousPerformRequestsWithTarget:self selector:@selector(hideControls)

  • bject:nil];
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Concurrency

iOS

TouchEvent Controller Update Views Idle

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[busyIndicator show]; [self performSelector:@selector(processData:) withObject:data afterDelay:0.0];

Concurrency

iOS

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Concurrency

iOS

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Concurrency

iOS

Queueing Model C-level API Blocks

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(^myBlock) (*myFunc)(int, int)

Concurrency

iOS

Blocks float = ...; = ^(int x, int y) { return x / (float)y; }; float result = myBlock(1, 2);

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(^myBlock)(int)

Concurrency

iOS

Blocks float = ^(int x) { return x / (float)y; }; float result = myBlock(1); int y = 2;

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Concurrency

iOS

Blocks (float (^)(int)) divideByY(int y) { return ^(int x) { return x / (float)y; }; } float (^divideBy2)(int) = divideByY(2); float result = divideBy2(1);

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Concurrency

iOS

Data *data = ...; id result = [self processData:data]; [view display:result]; [view show];

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iOS

Concurrency

Data *data = ...; id result = [self processData:data]; dispatch_async(dispatch_get_main_queue(), ^{ }); }); [view display:result]; [view show]; dispatch_async(dispatch_get_global_queue(0,0), ^{

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iOS

Concurrency

Cache *cache = ...; dispatch_queue_t cacheQ = dispatch_queue_create( “com.xyz.cache”, NULL); . . . Record *record = ...; dispatch_async(cacheQ, ^{ [cache addRecord:record]; }); . . . __block Record *result; dispatch_sync(cacheQ, ^{ result = [cache recordForKey:key]; });

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  • No garbage collection!
  • Reference counting instead
  • ObjC for Mac OS has GC.

iOS will too (soon? http:// bit.ly/95kn6f)

  • Low-memory notifications

Memory

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Memory

alloc = create retain = increase reference count release = decrease reference count autorelease = release later

1 +1

  • 1
  • 1
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Memory

  • 1. [retain] what you need later
  • 2. [release] what you alloc or retain
  • 3. [autorelease] what you return
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s

@interface Person { String *_firstName; String *_lastName; } ... @property String *firstName; @property String *lastName;

  • (String *)fullName;

... @end

Memory

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  • (void)setFirstName:(String*)newFirst {

}

Memory

[newFirst retain]; [_firstName release]; _firstName = newFirst;

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  • (void)setFirstName:(String*)newFirst {

}

Memory

[newFirst retain]; [_firstName release]; _firstName = newFirst; [person setFirstName [person getFirstName]];

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Memory

  • (String *)fullName {

String *full = [[String alloc] initWithFormat: “%s %s”, _firstName, _lastName]; return [full autorelease]; }

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Memory

  • (void)dealloc {

[_firstName release]; [_lastName release]; [super dealloc]; }

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Memory

Person *person = [[Person alloc] init]; person.firstName = “Patrick”; person.lastName = “Linskey”; String *fullName = [person fullName]; Log(fullName); [list add:person]; [person release]; . . . [list remove:person];

1 2 1

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Memory

[[NotificationCenter defaultCenter] addObserver:self selector:@selector(memoryWarning:) name:MemoryWarningNotification

  • bject:nil];

. . .

  • (void)memoryWarning:(Notification*)notification {

[cache clear]; ... }

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Memory

  • (void)viewDidUnload {

[view release]; view = nil; ... [super viewDidUnload]; }

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Testing

  • Xcode has not been a shining beacon in the

darkness here

  • Ships with SenTest and OCUnit
  • Integration is much better than in old

Xcodes (<= 3)

  • GHUnit* is also popular
  • Basically mandatory for old Xcodes

* https://github.com/gabriel/gh-unit

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The App Store

  • Walled Garden
  • Approval latency is unpredictable
  • Fast-delivery-cycle teams will find this

frustrating

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Beta Distribution

  • Can distribute beta builds to a limited

number of iOS devices*

  • Consider TestFlight

https://testflightapp.com/

* 100 - 500, depending on your specifics

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Questions?

plinskey@gmail.com @plinskey Thanks!