303 TANSTAAFL: Using Open Source iPhone UI Code

TANSTAAFL: using
open source iPhone UI
code
Jonathan Saggau (@jonmarimba)
Sounds Broken inc

Three20 image viewer

Apple Joe++

Demo
or... Julia Child impression

How to use three20 photo
views
Static Library; pay special attention to linker ﬂags on web
site.

<TTPhotoSource> conforming object, which vends:
<TTPhoto> conforming objects

Note: <TTModel, TTURLObject>

Um. What?

/**
* TTModel describes the state of an object that can be loaded from a
remote source.
*
* By implementing this protocol, you can communicate to the user the
state of network
* activity in an object.
*/
@protocol TTModel <NSObject>

/**
* An array of objects that conform to the TTModelDelegate protocol.
*/
- (NSMutableArray*)delegates;

/**
* Indicates that the data has been loaded.
*
* Default implementation returns YES.
*/
- (BOOL)isLoaded;

/**
* Indicates that the data is in the process of loading.
*
* Default implementation returns NO.
*/
- (BOOL)isLoading;

/**
* Indicates that the data is in the process of loading additional
data.
*
*/
- (BOOL)isLoadingMore;

/**
* Indicates that the model is of date and should be reloaded as
soon as possible.
*
*/
-(BOOL)isOutdated;

/**
* Loads the model.
*
* Default implementation does nothing.
*/
- (void)load:(TTURLRequestCachePolicy)cachePolicy more:(BOOL)more;

/**
* Cancels a load that is in progress.
*
*/
- (void)cancel;

/**
* Invalidates data stored in the cache or optionally erases it.
*
*/
- (void)invalidate:(BOOL)erase;

@end

@protocol TTURLObject <NSObject>
@optional

/**
* Converts the object to a URL using TTURLMap.
*/
@property (nonatomic, readonly) NSString* URLValue;

/**
* Converts the object to a specially-named URL using TTURLMap.
*/
- (NSString*)URLValueWithName:(NSString*)name;

@end

How it works

TTPhotoViewController and TTThumbsViewController

TTURLCache caches images to memory and / or disk

TTURLRequestQueue handles downloading images

@protocol TTPhotoSource <TTModel, TTURLObject>

/**
* The title of this collection of photos.
*/
@property (nonatomic, copy) NSString* title;

/**
* The total number of photos in the source, independent of the number
that have been loaded.
*/
@property (nonatomic, readonly) NSInteger numberOfPhotos;

/**
* The maximum index of photos that have already been loaded.
*/
@property (nonatomic, readonly) NSInteger maxPhotoIndex;

/**
*
*/
- (id<TTPhoto>)photoAtIndex:(NSInteger)index;

@end

@protocol TTPhoto <NSObject, TTURLObject>

/**
* The photo source that the photo belongs to.
*/
@property (nonatomic, assign) id<TTPhotoSource> photoSource;

/**
* The index of the photo within its photo source.
*/
@property (nonatomic) CGSize size;

/**
* The index of the photo within its photo source.
*/
@property (nonatomic) NSInteger index;

/**
* The caption of the photo.
*/
@property (nonatomic, copy) NSString* caption;

/**
* Gets the URL of one of the differently sized versions of the
photo.
*/
- (NSString*)URLForVersion:(TTPhotoVersion)version;

@end

can use bundle://someImageFileNameHere as URL string
to load images from app bundle

can use documents://someImageFileNameHere as
URL string to load images from user documents folder

Other cool stuff about three20

URL-based navigation that can persist the path taken to
get to a given view controller and can push that stack of
views back on when the user re-opens your app.

Stylesheets to “skin” your app easily.

Pretty buttons and overlays.

Decent (visual) error handling for cloud-based apps

Simpler UITableView programming using TTModel*

Documentation and help

Mailing list: http://groups.google.com/group/three20

API docs: http://three20.info/

Me! jonathan@jonathansaggau.com @jonmarimba

(I’m not afﬁliated with three20, I just use it a lot)

Calendar view with Kal

Apple Keith

303 TANSTAAFL: Using Open Source iPhone UI Code

@protocol KalDataSourceCallbacks;

@protocol KalDataSource <NSObject, UITableViewDataSource>
- (void)presentingDatesFrom:(NSDate *)fromDate to:(NSDate *)toDate delegate:
(id<KalDataSourceCallbacks>)delegate;
- (NSArray *)markedDatesFrom:(NSDate *)fromDate to:(NSDate *)toDate;
- (void)loadItemsFromDate:(NSDate *)fromDate toDate:(NSDate *)toDate;
- (void)removeAllItems;
@end

@protocol KalDataSourceCallbacks <NSObject>
- (void)loadedDataSource:(id<KalDataSource>)dataSource;
@end

Coverﬂow view with OpenFlow

Apple Alex

How to use it.
@protocol AFOpenFlowViewDataSource <NSObject>

//Tells the data source that will need this image.
//The data source should set the image as soon as it’s ready
- (void)openFlowView:(AFOpenFlowView *)openFlowView requestImageForIndex:(int)index;
- (UIImage *)defaultImage;

@end

//Allows the delegate to update other parts of UI for selection
@protocol AFOpenFlowViewDelegate <NSObject>
@optional
- (void)openFlowView:(AFOpenFlowView *)openFlowView selectionDidChange:(int)index;
@end

How to use it.
BTW: The sample code also has a useful image loading
subclass of NSOperation.

If you want to change the image for a given index, do
this:

[(AFOpenFlowView *)someView setImage:someImage forIndex:someInteger];

How it works
CoreAnimation 2.5D++

// Set some perspective

CATransform3D sublayerTransform = CATransform3DIdentity;

sublayerTransform.m34 = -0.01; // 1 / -zDistance where zDistance = 100

[scrollView.layer setSublayerTransform:sublayerTransform];

Dequeues images much like the UITableView
(and the TTPhotoview controller, too)
Draws only those images that are on screen
// the magic is here
- (void)layoutCover:(AFItemView *)aCover
selectedCover:(int)selectedIndex
animated:(Boolean)animated

Beware The Uncanny Valley.

Wikipedia User:Smurrayinchester (Creative Commons
Attribution ShareAlike 3.0)

What needs a-changin’
The animation is a little “off” for the rotation (seems like
it’s the wrong speed)

The z position of the flanking photos is not far enough
away.

Feels like there is a lot of friction.

The reflection under the covers is semi-transparent.
Apple’s view has the reflected images occlude those
behind as in “real life.”

How I “ﬁxed” it.
Hacking others’ code is fun (really)

Let a scroll view do the animating left to right and set
which page is selected (and therefore rotated to face the
user) based on screen centerline.
// UIScrollViewDecelerationRateNormal = 0.998
// UIScrollViewDecelerationRateFast = 0.990
self.decelerationRate = .992;

How I “ﬁxed” it.
scrolling a UIScrollView sets bounds constantly
and calls layoutSubviews a lot...
- (void)layoutSubviews
{
NSLog(@"[%@ %s]", self, _cmd);
halfScreenWidth = self.bounds.size.width / 2;
halfScreenHeight = self.bounds.size.height / 2;

int lowerBound = MAX(-1, selectedCoverView.number - COVER_BUFFER);
int upperBound = MIN(self.numberOfImages - 1, selectedCoverView.number + COVER_BUFFER);
// 1 / -zDistance where zDistance = 100
[self layoutCovers:selectedCoverView.number fromCover:lowerBound toCover:upperBound];
[self setNumberOfImages:numberOfImages]; // resets view bounds and stuff
CGPoint contentOffset = [self contentOffset];
int targetCover = (int) roundf(contentOffset.x / COVER_SPACING);
if (targetCover != selectedCoverView.number) {
if (targetCover < 0)
[self setSelectedCover:0];
else if (targetCover >= self.numberOfImages)
[self setSelectedCover:self.numberOfImages - 1];
else
[self setSelectedCover:targetCover];
}
}

Hijacking touch events
I think I stole this from Apple’s sample code

- (SBNotifyingWindow *)appWindow
{
id appDel = [[UIApplication sharedApplication] delegate];
if([appDel respondsToSelector:@selector(window)])
{
UIWindow *window = [appDel performSelector:@selector(window)];
if([window isMemberOfClass:[SBNotifyingWindow class]])
{
return (SBNotifyingWindow *)window;
}
}
return nil;
}

- (void)setUpInitialState {

[[self appWindow] addObjectInterestedInTouches:self];

#pragma mark SBNotifyingWindowTouches

-(void)interestingEvent:(UIEvent *)event;
{
//NSLog(@"%@ %s %@", self, _cmd, event);

NSSet *touches = [event allTouches];
UITouch *touch = [touches anyObject];
UITouchPhase phase = [touch phase];

if (phase == UITouchPhaseBegan) {
[self touchesBegan:touches withEvent:event];
}
if (phase == UITouchPhaseEnded)
{
[self touchesEnded:touches withEvent:event];
}
if (phase == UITouchPhaseCancelled) {
[self touchesCancelled:touches withEvent:event];
}
if (phase == UITouchPhaseMoved) {
[self touchesMoved:touches withEvent:event];
}
}

Coverﬂow view with OpenFlow

My mods of Alex’s
Apple awesome code
(ongoing)

To Do

The center view doesn’t quite center after you throw the view
around. (UIScrollview’s friction stops where it wants to)

Would like to add ﬂipping the front cover to another view and
add the rest of the UI in Apple’s implementation.

My mods are available on github at:
https://github.com/jonmarimba/OpenFlow

Other implementations

FlowCover (OpenGL ES)

Plausible Labs has one, too
(Not free, but very accurate)

Look for gogoDocs Google Docs
reader for iPhone and iPad. It’s in an
the app store in your pocket.

jonathan@jonathansaggau.com
http://jonathansaggau.com/blog
twit: @jonmarimba

Will Code for food.
Will, um, food for code.

jonathan@jonathansaggau.com
http://jonathansaggau.com/blog
twit: @jonmarimba

Nerds for hire // Hiring nerds

303 TANSTAAFL: Using Open Source iPhone UI Code

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