sorting - Sort two-dimensional NSMutableArray using the last element the inner arrays -


i have following nsmutablearray:

 (a|b|c|d|e|255,  f|g|h|i|j|122,  k|l|m|n|o|555)

i trying sort objects in array using last component (255, 122, 555). right have following code:

[myarray sortusingselector:@selector(localizedcaseinsensitivecompare:)];

as expected, method sorts array first element (a, f, k).

i read nssortdescriptor, example:

 nssortdescriptor *sort = [[[nssortdescriptor alloc] initwithkey:@"datemodified" ascending:yes] autorelease];

if use it, not clear put parameter in initwithkey.

you can use sort descriptor, takes last object of "inner" arrays , sort that.

since sort descriptors use key-value coding (kvc), need aware arrays respond valueforkey: in special way - pass normal key on each of objects contain.

you need know methods not take parameter and return value can accessed through kvc if normal properties.

all adds following:

  1. each of objects contained in array (i.e., inner arrays) have key want sort by: lastobject
  2. but since objects instances of nsarray pass key on objects they contain - not want.
  3. you therefore need use special escape in key name situation, @, making actual key use @lastobject

so make long story short, can want in way:

nsmutablearray *array = ... // array  nssortdescriptor *sd = [nssortdescriptor sortdescriptorwithkey: @"@lastobject"                                                      ascending: yes                                                        selector: @selector(localizedcaseinsensitivecompare:)];  [array sortusingdescriptors: @[sd]];

you'll notice "@" in key name, within string.

this escape character works other collection classes, instance if want access allkeys dictionary through kvc, key should use @allkeys.


Comments

Post a Comment

Popular posts from this blog

google app engine - 403 Forbidden POST - Flask WTForms -

i have flask application running on google app engine. trying submit form built using wtform , keep getting following error. 403 forbidden: don't have permission access requested resource. either read-protected or not readable server. location.html (part of code) <form method=post action="/home/location"> .... <button type="submit" class="btn btn-primary" value="submit"> directions </button> </form> main.py @app.route('/home/location', methods=['post', 'get']) def location(): form = cfcdirections.direction(request.form) print(request.method) if request.method == 'post' , form.validate(): print("after if") directions = cfcdirections() street_no = directions.no street = directions.street suburb = directions.suburb postcode = directions.postcode ...
Read more

how to run a query SQL in node.js mysql -

i have syntax problem in module, fail sql query. i initialize module database in file.js, responds console.log 'connected database', sends data module in database.newdata(data), when enters in runquery nothing happens, no errors or result, nothing! i in runquery if query ok , if this, think happens there error in logic of node, idea connect database , use runquery run query pass. file.js var db = require('./modules/database'); var database = new db(); database.newdata(data); database.js var mysql = require('mysql'), queries = require('./queries'), connection; var db = function(){ var db_config = { host: 'localhost', user: 'diegoug', password: 'qwertyuiop', database: 'test' }; connection = mysql.createconnection(db_config); connection.connect(function(err) { if(err) { console.log('error when connecting database:', err); ...
Read more

Android layout hidden on keyboard show -

i have strange problem layout. when tap on edittext , keyboard shown edittext stay on bottom , when tap on to hide keyboard , keyboard hides , edittext go should when want input text. when tap again, keyboard shown , edittext goes down behind keyboard... <relativelayout android:layout_width="match_parent" android:layout_height="match_parent" > <scrollview android:layout_width="match_parent" android:layout_height="fill_parent" android:above="@+id/rl_commands"> <textview android:layout_width="match_parent" android:layout_height="wrap_content"/> </scrollview> <relativelayout android:layout_width="match_parent android:layout_height="24dp" android:id="@+id/rl_commands" android:alignparentbottom="true"> ...
Read more