Objective-C Fundamentals

Scripting languages: Lua and Ruby
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if (image == nil)
NSLog(@"Do real error checking here");
GLuint width = CGImageGetWidth(image.CGImage);
GLuint height = CGImageGetHeight(image.CGImage);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
void *imageData = malloc(height * width * 4);
CGContextRef context = CGBitmapContextCreate(imageData, width, height,
8, 4 * width, colorSpace,
kCGImageAlphaPremultpliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
CGRect imageRect= CGRectMake(0, 0, width, height);
CGContextClearRect(context, imageRect);
CGContextTranslateCTM(context, 0, height - height);
CGContextDrawImage(context, imageRect, image.CGImage);
glTexImage2D(GL_TEXTURE_2D 0, GL_RGBA, width, height, 0,
GL_RGBA, GL_UNSIGNED_BYTE, imageData);
CGContextRelease(context);
free(imageData);
[image release];
[texData release];
Technologies such as the Corona SDK are opening iPhone application development
to a wider range of people; development isn’t necessarily restricted to those with a
strong programming background. A key premise to this type of technology is that the
higher-level scripting languages make development more accessible and forgiving
than in languages in which hard-to-detect-and-diagnose errors can occur (such as
Objective-C, which allows you to get closer to the hardware). In this case, the trade-off
of not having immediate access to all hardware of the operating system features can
be deemed to be acceptable. If Lua isn’t your cup of tea, chances are, with a little
research online, you’ll be able to find an equivalent solution for your language of
choice. For example, Ruby developers can use an open source framework called
Rhodes (http://rhomobile.com/products/rhodes/) to develop native applications
that work across a number of mobile platforms (iPhone, Windows Mobile, RIM,
Symbian, Android, MeeGo, and Windows Phone 7) while working with device capabilities
such as GPS, PIM information, camera, mapping, signature capture, and Bluetooth.
The trade-off in using a platform such as Corona is that you may be restricted to a
particular subset of device features supported by the product. Using a similar argument
to that used for web applications, scripting languages will potentially always lag behind,
if only because they require a wrapper to be developed with every API the developer
wants to be accessible from the scripting language. This is especially true when you
consider that many of these platforms also attempt to be cross-platform solutions so, in
some cases, they purposely don’t expose a feature of a specific platform if that feature
would be hard or impossible to provide on another supported device type. You, in
effect, obtain a lowest-common-denominator development platform.
Scripting languages also have to be careful not to run afoul of the iPhone OS SDK
license agreement terms, which every developer must accept in order to develop and