IOS 7 pushing the Limits-good & bad namings in Cocoa

Cocoa is a dynamically typed language, and you can easily get confused on what the type you were working with.
Collections (arrays, dictionaries, and so on) don ' t has types associated with them, so it's very easy to code
Something accidentally like this:

Nsarray *dates = @[@ "1/1/2000"];
NSDate *firstdate = [dates firstobject];

This code compiles without a warning, but would crash with an unknown
Selector exception.

Let's look at following code lines:

-(void) SetUrl: (NSString *) URL; Bad

-(void) seturlstring: (NSString *) string; Good
-(void) SetUrl: (Nsurl *) URL; Good

Category methods

Because of the possibility of collisions, you should add a prefix to your category methods

Cocoa generally doesn ' t use embedded underscores

A good use of categories are to provide utility methods to existing classes. When did this, I recommend
Naming the header and implementation files using the name of the original class plus the name of the
Extension.

For example, you might create a simple ptlextensions category on NSDate:

Nsdate+ptlextensions.h

@interface nsdate (ptlextensions)- (Nstimeinterval) Ptl_timeintervaluntilnow; @end

Nsdate+ptlextensions.m

@implementation nsdate (ptlextensions)- (nstimeinterval) ptl_timeintervaluntilnow {  return -[ Self timeintervalsincenow];} @end