TEchnical Cites

Core Data takes care of the life-cycle o …

praveenmatanam — Fri, 01 Jul 2011 06:03:23 +0000

Core Data takes care of the life-cycle of the modeled properties, in a reference-counted environment you do not release modeled properties in dealloc.

For performance reasons, Core Data typic …

praveenmatanam — Fri, 01 Jul 2011 06:02:13 +0000

For performance reasons, Core Data typically does not copy object values, even if the value class adopts the NSCopying protocol.

Core Text layout engine is up to twice a …

praveenmatanam — Thu, 24 Jun 2010 05:13:45 +0000

Core Text layout engine is up to twice as fast as ATSUI (Apple Type Services for Unicode Imaging). The Core Text layout API is simple, consistent, and tightly integrated with Core Foundation, Core Graphics, and Cocoa.

Instead, you need to use a different tec …

praveenmatanam — Fri, 07 May 2010 10:36:43 +0000

Instead, you need to use a different technique, which is the check the precompiler definition __IPHONE_OS_VERSION_MAX_ALLOWED, which is set to the OS version number without dots. The definition is five digits, the first is the major release number, the second and third are the minor release number, and the fourth and fifth number are the patch release number. So, 3.2 would be defined to 30200 and 3.1.2 would be defined to 30102, so here’s how you should probably design your code for the time being:

If a gesture recognizer detects a touch …

praveenmatanam — Mon, 03 May 2010 04:49:36 +0000

If a gesture recognizer detects a touch (as represented by a UITouch object) that it determines is not part of its gesture, it can pass it on directly to its view. To do this, it calls ignoreTouch:forEvent: on itself, passing in the touch object. Ignored touches are not withheld from the attached view even if the value of the cancelsTouchesInView property is YES.

Most version-related behavior changes ar …

praveenmatanam — Wed, 28 Apr 2010 09:19:46 +0000

Most version-related behavior changes are listed in the framework release notes, but they are not necessarily described in the reference documentation. To understand the differences from one release to another, you must carefully review the release notes.

The iPod touch (3rd generation) can be d …

praveenmatanam — Tue, 27 Apr 2010 13:55:44 +0000

The iPod touch (3rd generation) can be distinguished from iPod touch (2nd generation) by looking at the back of the device. In the text below the engraving, look for the model number. iPod touch (2nd generation) is model A1288, and iPod touch (3rd generation) is model A1318.

Here are a few general guidelines for fi …

praveenmatanam — Fri, 02 Apr 2010 05:23:05 +0000

Here are a few general guidelines for finding a good candidate for optimization:

It should be time-critical. This is generally any operation that is perceptibly slow; the user has to wait for the computer to finish doing something before continuing. Optimizing functionality that is already faster than the user can perceive is usually unnecessary.
It must be relevant. Optimizing functionality that is rarely used is usually counter-productive.
It shows up as a hot spot in a time profile. If there is no obvious hot spot in your code or you are spending a lot of time in system libraries, performance is more likely to improve through high-level improvements (architectural changes).

Literal characters may also be specified …

praveenmatanam — Fri, 12 Mar 2010 10:12:55 +0000

Literal characters may also be specified using their numeric code value. The general escape sequence \ooo (i.e., a backslash followed by up to three octal digits) is used for this purpose. For example (assuming ASCII):
‘\12′ // newline (decimal code = 10)
‘\11′ // horizontal tab (decimal code = 9)
‘\101′ // ‘A’ (decimal code = 65)
” // null (decimal code = 0)

a union may not have a static data membe …

praveenmatanam — Fri, 12 Mar 2010 09:42:58 +0000

a union may not have a static data member or a data member which requires a constructor.