devLink presentation: New Features for iPad and iOS 4 SDK

source | slides

devLink presentation: iOS SDK: Core Data

source | slides

devLink presentation: Introduction to the iOS SDK

Here's the slide deck and source code for my "Introduction
to the iOS SDK" talk. Thanks for coming to devLink. Hope you had a great time!

source | slides

Custom tintColor for each segment of UISegmentedControl

The UISegmentedControl offers the ability to set the tint color for the entire control, but it does not offer the ability to set the tint color for an individual segment. In fact, the UISegment class, the actual class for the individual segments, is not publicly documented. So, what I propose here does go a bit off the farm, but it only uses publicly available API to accomplish it. Here is the end result.

The first step is to create an extension to the UISegmentedControl. The extension neatly wraps up the new functionality so that it can be easily reused instead of cluttering up your view controllers.

UISegmentedControlExtension.h

@interface UISegmentedControl(CustomTintExtension)
-(void)setTag:(NSInteger)tag forSegmentAtIndex:(NSUInteger)segment;
-(void)setTintColor:(UIColor*)color forTag:(NSInteger)aTag;
-(void)setTextColor:(UIColor*)color forTag:(NSInteger)aTag;
-(void)setShadowColor:(UIColor*)color forTag:(NSInteger)aTag;
@end

UISegmentedControlExtension.m

#import "UISegmentedControlExtension.h"


@implementation UISegmentedControl(CustomTintExtension)

-(void)setTag:(NSInteger)tag forSegmentAtIndex:(NSUInteger)segment {
[[[self subviews] objectAtIndex:segment] setTag:tag];
}

-(void)setTintColor:(UIColor*)color forTag:(NSInteger)aTag {
// must operate by tags.  Subview index is unreliable
UIView *segment = [self viewWithTag:aTag];
SEL tint = @selector(setTintColor:);

// UISegment is an undocumented class, so tread carefully
// if the segment exists and if it responds to the setTintColor message
if (segment && ([segment respondsToSelector:tint])) {
 [segment performSelector:tint withObject:color];
}
}

-(void)setTextColor:(UIColor*)color forTag:(NSInteger)aTag {
UIView *segment = [self viewWithTag:aTag];
for (UIView *view in segment.subviews) {
 SEL text = @selector(setTextColor:);

 // if the sub view exists and if it responds to the setTextColor message
 if (view && ([view respondsToSelector:text])) {
  [view performSelector:text withObject:color];
 }
}
}

-(void)setShadowColor:(UIColor*)color forTag:(NSInteger)aTag {

// you probably know the drill by now
// you could also combine setShadowColor and setTextColor
UIView *segment = [self viewWithTag:aTag];
for (UIView *view in segment.subviews) {
 SEL shadowColor = @selector(setShadowColor:);
 if (view && ([view respondsToSelector:shadowColor])) {
  [view performSelector:shadowColor withObject:color];
 }
}
}

@end

Once that is in place, here is an example of a typical UIViewController taking advantage of it.

SegmentColorsViewController.m

#import "SegmentColorsViewController.h"
#import "UISegmentedControlExtension.h"

#define kTagFirst 111
#define kTagSecond 112
#define kTagThird 113

@interface SegmentColorsViewController(PrivateMethods)
-(void)segmentChanged:(id)sender;
-(void)setTextColorsForSegmentedControl:(UISegmentedControl*)segmented;
@end

@implementation SegmentColorsViewController

-(void)viewDidLoad {

// create a simple segmented control
// could have done this in Interface Builder just the same
NSArray *items = [[NSArray alloc] initWithObjects:@"orange", @"yellow", @"green", nil];
UISegmentedControl *colors = [[UISegmentedControl alloc] initWithItems:items];
[items release];
[colors setSegmentedControlStyle:UISegmentedControlStyleBar];
[colors setTintColor:[UIColor lightGrayColor]];
[colors setFrame:CGRectMake(20.0f, 20.0f, 280.0f, 30.0f)];
[colors addTarget:self action:@selector(segmentChanged:) forControlEvents:UIControlEventValueChanged];
[self.view addSubview:colors];


// ... now to the interesting bits

// at some point later, the segment indexes change, so
// must set tags on the segments before they render
[colors setTag:kTagFirst forSegmentAtIndex:0];
[colors setTag:kTagSecond forSegmentAtIndex:1];
[colors setTag:kTagThird forSegmentAtIndex:2];

[colors setTintColor:[UIColor orangeColor] forTag:kTagFirst];
[colors setTintColor:[UIColor yellowColor] forTag:kTagSecond];
[colors setTintColor:[UIColor greenColor] forTag:kTagThird];

[self setTextColorsForSegmentedControl:colors];
[colors release];
}

-(void)segmentChanged:(id)sender {
// when a segment is selected, it resets the text colors
// so set them back
[self setTextColorsForSegmentedControl:(UISegmentedControl*)sender];
}

-(void)setTextColorsForSegmentedControl:(UISegmentedControl*)segmented {
[segmented setTextColor:[UIColor yellowColor] forTag:kTagFirst];
[segmented setTextColor:[UIColor blackColor] forTag:kTagSecond];
[segmented setTextColor:[UIColor blueColor] forTag:kTagThird];

[segmented setShadowColor:[UIColor redColor] forTag:kTagFirst];
[segmented setShadowColor:[UIColor whiteColor] forTag:kTagSecond];
[segmented setShadowColor:[UIColor clearColor] forTag:kTagThird];
}
@end

Pre-compiled Libraries for iPhone OS

Digging into the RedLaser SDK. Their sample includes several ".a" files that seem to contain all the real magical guts of the their product. Intrigued. This link describes how to create such a thing for myself.

UPDATE: Here are a few other similar links:

• StackOverflow: A Guide for Creating your own Library for Cocoa(touch) development
• StackOverflow: Can I develop my own objective-C Framework for Cocoa Touch Applications?
• Building static libraries with the iPhone SDK
• StackOverflow: How do I add a third party Framework to iPhone project?

iPhone / iPad Universal Binary notes

Building a universal binary for iPhone / iPad seems a bit unintuitive. Started in XCode by selecting my target, then, in the menu, choose Project -> Upgrade Current Target for iPad…

After that, a build yielded the following warning:

"warning: building for deployment target '3.2' should omit the armv6 architecture."

Select the project, click Info, change the following values:

Base SDK: Optimized (armv6 armv7)

Build Active Architecture Only: NO

Targeted Device Family: iPhone/iPad

iPhone OS Deployment Target: iPhone OS 3.1.3

Should get rid of warning and build and debug on iPad.

When building for the iPhone, don't switch the build target back to 3.1.3. Keep using 3.2.

Free Version and in-app purchases

Researching building a free version of an iPhone app and a paid version of the same app that includes in-app purchases.

I got started by copying the target bundle in XCode to create MyApp and MyAppFree. One of my first questions is, how do I handle the bundle id and app id? Found this at StackOverflow that sent me in a slightly different direction:

http://stackoverflow.com/questions/2146097/app-id-and-bundle-seed-id-in-multiple-applications-with-aspn-inapp-purchase-and

particularly:

"…Apple has frowned on having both a "Lite" version as well as an "in-app" updatable version. One or the other. Recently they have been pushing the "in-app" updatable…"

uh oh ... led to this:

http://www.tuaw.com/2009/10/15/apple-relents-in-app-purchase-for-free-apps-allows-demo-to-paid/

So, can have one version of the app instead of free version and full version.

Next read was "App Store Quick Reference: Getting Started with In App Purchase on iPhone OS".

https://developer.apple.com/iphone/news/pdf/in_app_purchase.pdf

http://developer.apple.com/iphone/news/appstoretips/

I read no definitive prohibition against building both a free and an in-app purchase version, but feel that I should be better safe than sorry.