iPhoneDevelopmentBits » iPhone Games

Gyroscope: The New Opportunity [U]

anup — Tue, 29 Jun 2010 13:01:51 +0000

While the entire world was giddily anticipating the start of World Cup soccer this year, it was nose to the grindstone here at Sourcebits developing new soccer madness updates of Funbooth for Mac and iPhone. Work notwithstanding, our development team had serious fun during production of these applications. Throughout the beta testing and QA we were constantly capturing images of ourselves in the props of the teams we support, and we made the most of the new social features with the on-the-fly uploading to Facebook and Twitter. And at the same time, our gaming wing guys at Wandake were busy putting the finishing touches on their now-huge hit Wake Up the Box! for iPhone and iPad. So it was a real party at times.

While all this was going on, of course there was some big news on June 7, when Steve Jobs introduced yet another Apple engineering marvel: iPhone 4. Bundled with new features like front-facing camera, superior rear camera, dual mikes for increased noise cancellation, eye-popping Retina Display, multitasking, 720p HD video recording and even a new kind of gyroscope technology, iPhone 4 is a huge evolutionary step in smartphone design. As the tag line says: “This changes everything. Again.” And, marketing hyperbole aside, as far as day-to-day use is concerned for sure this will change the way we use iPhone.

Before this year’s launch, several leaked – or mislaid – iPhone 4 models made the rounds of the major tech blogs, complete with gory dissections and the standard tsunami of specu-babble. But there was one stealth feature all the teardowns and pundits failed to even guess at: the gyroscope. And on our side, as veteran iPhone developers, when Steve Jobs announced this during WWDC we were all pretty excited. And while it still hasn’t gotten much attention in the press, this feature is a game changer in iPhone’s rivalry with Android and Symbian devices.

Apple’s been pioneering smartphone innovations since iPhone’s introduction in 2007 with many widely imitated micro-technologies, in particular the accelerometer. The accelerometer is a type of sensor that detects changes in a device’s orientation, vibration, rotation or fall by detecting linear acceleration along one of the three X, Y and Z axes – that is: up/down, right/left, and front/back.

3-axis accelerometers enable features we by now take for granted in smartphones (and lately, too, in non-Apple branded consumer digital cameras, music players, and gaming peripherals). For example, landscape/portrait orientation shifting, tilt for directional control in games and applications, and shake features for refreshing a webpage or shuffling a playlist. The 1st generation of accelerometer – pre iPhone 4 – could measure only linear motion; it couldn’t sense direction on a compass or twisting motions or rotation, nor had any notion of gravity.

Then last year Apple added a magnetometer to the iPhone 3Gs, enabling it to sense magnetized direction relative to the Earth’s poles. And now, with the introduction of the gyro in iPhone 4, Apple once more ups the ante in spatial detection / orientation with a new sensor for detecting 3-axis angular acceleration around the X,Y and Z axes, enabling far more precise virtualization of pitch, yaw and roll on iPhone.

While detection of change in velocity has been possible for some time thanks to conventional accelerometer calculations in terms of linear acceleration, the gyroscope has been designed to detect angular acceleration, which will detect change in both velocity and direction at the same time. iPhone 4’s gyroscope enables the sensing of even slight degrees of rotation while simultaneously rejecting linear movements and hand jitters – both still ably handled by accelerometer’s linear movement detection technology.

Combining the 3 axes of the gyroscope along with the 3 axes of the accelerometer now enables iPhone to recognize distance, speed and direction as it moves real-time through space. And thanks to the CoreMotion APIs in iOS, developers with the vision to make use of gyroscope data can access it freely, as some have already done.

Of course iPhone 4 already includes gyroscope support, but it’s a safe bet the gyro will be baked into future versions of iPod touch, and naturally, iPad. iPhone devs who can make use of this amazing new technology will find opportunities aplenty on the new platforms, especially games producers and developers.

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update: Death Star or iPhone gyroscope? iFixit has the goods.

Native Frameworks for adding Network Connectivity to your iPhone Applications

rohit — Mon, 25 Jan 2010 10:11:37 +0000

Tons of new frameworks for iPhone developers to use that will should really simplify networking, credit card processing, shipping & tracking, banking, etc. for iPhone applications. Only one glitch its all commercial! You can find more info about them at Nsoftware.

• IP*Works! – A comprehensive suite of Internet components for professional developers (FTP, IMAP, POP, LDAP, SNMP, SOAP, etc.).
• IP*Works! SSL – Secure implementations of every major SSL-enabled Internet protocol
• IP*Works! S/MIME – Components for S/MIME e-mail and file signing and encryption.
• IP*Works! S/Shell – Add Instant Secure Shell (SSH) Security to your applications.
• IP*Works! Secure SNMP – Components for building Secure SNMP Agents and Managers
• IP*Works! Zip – An easy, fast, and effective suite of compression components.
• QuickBooks Integrator – Components for QuickBooks and Merchant Services integration.
• E-Payment Integrator – Credit card and ACH processing through Internet Gateways.
• E-Banking Integrator – Components for Open Financial eXchange (OFX) client integration.
• Shipping Integrator – Shipping and Tracking components via FedEx, USPS, & UPS.
• Amazon Integrator – Components for Amazon Web Services including S3, SQS, and ECS

Unit Level Developer Testing for iPhone Applications

rohit — Mon, 28 Dec 2009 08:55:02 +0000

Matt Gallagher writes an excellent article about unit level testing for iPhone applications and explain in detail the logic and application tests in a real world development environment using a test application as example. He is generous enough to post the code of the application as well.

[source CocoawithLove]

Good programming practices ( Object Oriented / C++)

shihab — Fri, 30 Jan 2009 18:40:36 +0000

Some of the best practices given below.

1. Prefer inline function over macros, bcz macro willl bring unwanted errors.

eg: See the example of a macro to find maximum of two numbers

#define MAX(a,b) (a > b) ? a : b

suppose if we used the macro as follows

int x = 20, y = 19;

int z = MAX(x, ++y);

now what is the value of z ? is it 20 ? or is it 19 ? .

.. he he …it is 21 !

Let us see , how it is happened,

Compiler will compile the code after macro expansion .. after macro expansion , the code will be as follows

int x = 20, y = 19;

int z = (x > ++y) ? x: ++y;

y has been incremented twice .. !

What is the solution:-

Use inline function… it will not produce unwanted errors … and high fast like macros bcz there is no function calling burdens

Avoid complex expression when using macros… ie we can call the MAX as follows

int x = 20, y = 19;

++y;

int z = MAX(x, y);

2. Use call by reference other than call by value for big user defined data types.

//suppose we are having a class MyClass of size 100 bytes;

void foo(MyClass m) {

//some code

}

——————Instead use as follows ———————————

void foo(const MyClass& m) {

//some code

}

Explanation:

In both case we can call the method as follows

MyClass mc;

foo(mc);

In the first case a value of MyClass object, mc is copied to another object m, of MyClass.

Here Object of the MyClass has been created twice ie total 200 bytes used ..

also it will bring extra processing to initialize a new object.

In the second case , MyClass object is created only once then the alias of mc is created as m

there is no burden of new object initialization and processing.

The ‘const’ is used for two reason…

a) To avoid the misunderstanding that it is an output argument.

b) To avoid the accidental changes to the outside object from the function.

Note:- In C there is no call by reference but we are simulating call by reference

by passing address to the function argument and modifying the content of the address

from the function

3. Avoid unwanted file inclusion and prefer forward declaration.

Suppose Foo is a class and its definition is in Foo.h.

We are using the class Foo in the File MyClass.h as follows.

//MyClass.h

#include “Foo.h”

class MyClass {

Foo * aFoo;

//Some methods

}

———— Instead use as follows ————–

//MyClass.h

class Foo; // forward declaration.

class MyClass {

Foo * aFoo;

//Some methods

}

Explanation: -

In the first case, when including Foo.h , the entire code will be pasted in MyClass.h, it will

increase the size of executable and will creep in some unwanted errors.

We are not instantiating, or using the functionality of Foo, so the compiler should not bother about the size

of the class Foo ..it wants to know only what is Foo, we have forward declared it as ‘Class’.

Also aFoo is a pointer, the size of any pointer is the size of an integer.

so the compiler can allocate the size of pointer and it will not produce any error message.

4. Use header guard to avoid multiple inclusion of a file.

Interesting tidbits for OpenGL programming on iPhone

rohit — Wed, 24 Dec 2008 09:29:44 +0000

I have been following this blog for sometime and must say the author Wolfgang Engel is posting some of the best tips for game programmers on iPhone. A must bookmark for every iPhone programmer.

Oolong Game Engine for iPhone

rohit — Mon, 08 Dec 2008 01:59:57 +0000

The Oolong Engine is written in C++ with some help from Objective-C. It will help you to create new games and port existing games to the iPhone and the iPod touch. The best part is, its free.

IMA4 Audio Programming for iPhone game developers

rohit — Mon, 08 Dec 2008 01:57:18 +0000

IMA-ADPCM is a compression standard that gets you 4:1 compression on 16-bit audio files. It’s supported natively by the iPhone — but only using certain APIs. Read the full article here.

[source Wooji-Juice]

iPhone programming screencasts

rohit — Wed, 22 Oct 2008 04:29:23 +0000

Informative iPhone programming screencasts.

[source MacHappens]

Tris sourcecode on Google Code

rohit — Tue, 14 Oct 2008 12:24:57 +0000

This game got banned on Appstore but still it is a very valuable resource to understand how to develop a game for iPhone. You can download the source code of Tris on google code.

31 iPhone apps in 31 days

rohit — Tue, 14 Oct 2008 12:17:56 +0000

Apps Amuck is writing 31 iPhone applications in the next 31 days and they will also publish both the executable and the source code for each application. This looks like a great resource for developers who will like to jump into iPhone application development.

[source Apps Amuck]

PhoneGap – Bridge between iPhone SDK and Web apps

rohit — Mon, 13 Oct 2008 09:57:06 +0000

PhoneGap is a free open source development tool and framework that allows web developers to take advantage of the powerful features in the iPhone SDK from HTML and JavaScript. It is written in Objective-C and allows developers to embed their web app (HTML, JavaScript, CSS) in Webkit within a native iPhone app.

PhoneGap is developed and designed by Brock Whitten, Rob Ellis, freelance designer Colin Toomey and Eric Oesterle.

[source PhoneGap]