Three20 Tidbits

Adapted from sujee.net

Three20 is an open source iPhone/iPad library that packs a lot of cool features. Three20 is popular for its UI components such as TTNavigator, TTWebController, TTPhotoViewController.

Also there is lot more than UI in Three20. I use Three20 sparingly in my iOS projects. I don't build my app as a 'full-blown Three20 app'. I use some components to save myself from re-inventing the wheels. That is what I will focus on here.

Getting Started

Follow steps in the article Introduction on how to incorporate Three20 into your iphone/ipad project.

Include

#import "Three20/Three20+Additions.h"

in the file where you want to use the functions.

NSString Additions

Code : NSStringAdditions

Check whitespace

To see if strings only have white space.

NSLog(@"\n\n====== NSString : white space =======");
NSString* ws = @" \t\n";
NSString* empty = @"    ";
NSString* nws = @"hello";
NSLog(@"'%@' contains only whitespace ? : %d", ws, [ws isWhitespaceAndNewlines]);
NSLog(@"'%@' contains only whitespace ? : %d", nws, [nws isWhitespaceAndNewlines]);       
NSLog(@"'%@' is empty? : %d", empty, [empty isEmptyOrWhitespace]); 

Output:

====== NSString : white space =======
'  
' contains only whitespace ? : 1
'hello' contains only whitespace ? : 0
'    ' is empty? : 1

Strip HTML tags

Handy for displaying user-entered data (comment/feedback) on UIWebView. We want to strip the HTML and only show text.

NSLog(@"\n\n====== NSString : stripHTML =======");
NSString* html = @"I <b>am</b> an HTML script.";
NSString* stipped = [html stringByRemovingHTMLTags];
NSLog(@"html : %@", html);
NSLog(@"stripped : %@", stipped);

Output:

NSLog(@"\n\n====== NSString : stripHTML =======");
html : I <b>am</b> an HTML script.
stripped : I am an HTML script.

Parsing URL query parameters

Parse URL query parameters and put them in a nice NSDictionary

NSLog(@"\n\n====== NSString : parse URL params =======");
NSURL* url = [NSURL URLWithString:
  @"http://www.google.com/search?sourceid=chrome&;ie=UTF-8&q=pizza"];
NSString* paramString = [url query];
NSDictionary* params = [paramString queryDictionaryUsingEncoding:NSASCIIStringEncoding];
NSLog(@"url : %@", url);
NSLog(@"params:\n%@", params);

Output:

====== NSString : parse URL params =======
url : http://www.google.com/search?sourceid=chrome&;ie=UTF-8&q=pizza
params:
{
    ie = "UTF-8";
    q = pizza;
    sourceid = chrome;
}

Create a URL from parameters

Create a valid query string from an NSDictionary

NSLog(@"\n\n====== NSString : create URL query string =======");
NSString* baseUrl = @"http://www.yahoo.com/search";
NSMutableDictionary* params = [[NSMutableDictionary alloc] init];
[params setValue:@"pizza" forKey:@"q"];
[params setValue:@"json" forKey:@"format"];
NSString* fullURL = [baseUrl stringByAddingQueryDictionary:params];
NSLog(@"query parameters\n%@", params);
NSLog(@"query string is : %@", fullURL);

Output:

====== NSString : create URL query string =======
query parameters
{
    format = json;
    q = pizza;
}
query string is : http://www.yahoo.com/search?q=pizza&;format=json

md5 hash

When you want to md5 hash a string.

NSLog(@"\n\n====== NSString : md5 =======");
NSString* s1 = @"hiya Three20 world";
NSString* md5 = [s1 md5Hash];
NSLog(@"md5('%@') =>  %@", s1, md5);

Output:

====== NSString : md5 =======
md5('hiya Three20 world') =>  6fd98ef06e6041b87dbe8dc978b95c4c
md5Hash is also available for NSData

Version Compare:

For example, is "3.5" > "3.0.1"?

NSLog(@"\n\n====== NSString : version check =======");
NSString* v1 = @"2.5";
NSString* v2 = @"3.0";
NSString* v3 = @"3.0.1";
NSLog(@"%@ <=> %@  is %d", v2, v1, [v2 versionStringCompare:v1]);
NSLog(@"%@ <=> %@  is %d", v1, v2, [v1 versionStringCompare:v2]);
NSLog(@"%@ <=> %@  is %d", v3, v2, [v3 versionStringCompare:v2]);
NSLog(@"%@ <=> %@  is %d", v3, v3, [v3 versionStringCompare:v3]);

Output:

====== NSString : version check =======
3.0 <=> 2.5  is 1
2.5 <=> 3.0  is -1
3.0.1 <=> 3.0  is 1
3.0.1 <=> 3.0.1  is 0

NSDate Additions

File : NSDateAdditions

There are a lot of goodies here. My favorite is 'relative time'... like '2 hours ago', 'few minutes ago' ...etc.

Also it has handy functions to create various dates with ease (check the header file).

NSLog(@"\n\n====== NSDate : format =======");
NSDate* todayMidnight = [NSDate dateWithToday];
NSLog(@"today midnight date is : %@", [todayMidnight formatDate]);

NSDate* timeNow = [[NSDate alloc] init];
NSDate* fewDaysBack = [[NSDate alloc] initWithTimeIntervalSinceReferenceDate:
  [timeNow timeIntervalSinceReferenceDate] - (3600*24 * 4)];

NSLog(@"\n\n====== NSDate : relative time =======");

NSLog(@"today midnight was : %@", [todayMidnight formatRelativeTime]);
NSLog(@"just now was : %@", [timeNow formatRelativeTime]);
NSLog(@"few days back was (short format) : %@ ago",
  [fewDaysBack formatShortRelativeTime]);

Output:

====== NSDate : format =======
today midnight date is : Thursday, August 19, 2010

====== NSDate : relative time =======
today midnight was : 23 hours ago
just now was : just a moment ago
few days back was (short format) : 4d ago

Network Activity Indicator

File : TTGlobalNetwork

When you have multiple network requests going on (different threads ..etc), here is a handy function to keep the network indicator spinning straight.... TTNetworkRequestStarted(); //..... TTNetworkRequestStopped();

Common UI Stuff

File : TTGlobalUICommon

Some goodies here.... Functions for checking OS Version and if running iPad..etc

TTImageView

File : TTImageView

This is a drop-in replacement for any UIImageView, where image has to be loaded from a URL. All you do is feed a URL and it does the rest (starts downloading the image, shows placeholder image while downloading, and displays the image)! Self-contained. Also uses TTURLCache, so if the image has already been downloaded, it will not downloaded it, will just use from cache... cool!

// create TTImageView,
// this can be done programatically, or change the class name
// to 'TTImageView' in Interface Builder
TTImageView* imgView = [[TTImageView alloc] init];
// default image is displayed unitll the image is downloaded
imgView.defaultImage = [UIImage imageNamed:@"place-holder.png"];
// give it a URL to load image from
imgView.urlPath = @"image url path";

// now set the imageView to where ever you want
// self.imageView = imgView

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