GHKit defines various categories and general purpose utilities.

For example, parsing date strings, generating time ago in words, generating SHA1-HMAC, MD5, or special invocation proxies.

Source: http://github.com/gabriel/gh-kit

View docs online: http://gabriel.github.com/gh-kit/

Install the docset:

• Open Xcode, Preferences and select the Downloads / Documentation tab.
• Select the plus icon (bottom left) and specify: http://gabriel.github.com/gh-kit/publish/me.rel.GHKit.atom

Use the framework:

#import <GHKit/GHKit.h>

Dates:

GHNSDate+Formatters.h: Date parsers, formatting and formatters for ISO8601, RFC822, HTTP (RFC1123, RFC850, asctime) and since epoch.

 NSDate *date = [NSDate gh_parseISO8601:@"2010-10-07T04:25Z"]
 NSString *dateString = [date gh_formatHTTP]; // Formatted like: Sun, 06 Nov 1994 08:49:37 GMT"

GHNSDate+Utils.h: For time ago in words and date component arithmentic (adding days), tomorrow, yesterday, and more.

 NSDate *date = [NSDate date];
 [date gh_isToday]; // YES
 [[date gh_yesterday] gh_isToday]; // NO

 date = [date gh_addDays:-1];
 [date gh_wasYesterday]; // YES

 [date gh_timeAgo:NO]; // @"1 day"

Strings:

GHNSString+Utils.h: Stripping, reversing, counting, UUID, MD5 and more.

 [NSString gh_isBlank:@"  "]; // YES
 [NSString gh_isBlank:nil]; // YES
 [@"abc" gh_reverse]; // @"cba" 
 [@"  some text " gh_strip]; // @"some text"

URLs:

GHNSURL+Utils.h: Encoding, escaping, parsing, splitting out or sorting query params, and more.

NSDictionary *dict = [@"c=d&a=b" gh_queryStringToDictionary]; // Dictionary with a => b, c => d
[NSDictionary gh_dictionaryToQueryString:dict sort:YES]; // @"a=b&c=d"

Invocation:

GHNSObject+Invocation.h:

[[obj gh_proxyOnMainThread] myMethodWithInteger:4 string:@"string"]; // Call myMethod on main thread

[[array gh_proxyAfterDelay:2.0] insertObject:@"foo" atIndex:0]; // Inserts object after 2 second delay

SEL selector = @selector(bar:baz:);
[foo gh_argumentProxy:selector] arg:10 arg:YES];

Will call [foo bar:10 baz:YES]; (and not arg:arg: selector which doesn’t exist).

Files:

GHNSFileManager+Utils.h: File size, exists, generating temporary or unique file paths.

HMAC:

GHNSString+HMAC.h: SHA-1 HMAC

#import "GTMBase64.h"
["stringtosign" gh_HMACSHA1:@"secret" base64Encoder:[GTMBase64 class]];

Keychain:

Secret from keychain:

 GHKeychainStore *keyChainStore = [[GHKeychainStore alloc] init];
 NSError *error = nil;
 NSString *secret = [keyChainStore secretFromKeychainForServiceName:@"MyApp" key:"password" error:&error];
 if (!secret) NSLog(@"Error: %@", [error localizedDescription];

Save to keychain:

 GHKeychainStore *keyChainStore = [[GHKeychainStore alloc] init];
 NSError *error = nil;
 BOOL saved = [keyChainStore saveToKeychainWithServiceName:@"MyApp" key:"password" secret:"12345" error:&error];
 if (!saved) NSLog(@"Error: %@", [error localizedDescription];

And more…