I'm working on a project and I want to be able to handle some template type messages. The template would contain something like:
"{{user1}} has just created an account"
I then have a data map that would give you a location within the NSMutableDictionary where the data is located:
"activity.message.status"
I then want to be able to query the NSMutableDictionary by splitting up that string, so that it becomes something like:
[[[myDictionary objectForKey:#"activity"] objectForKey:#"message"] objectForKey:#"status"]
I could make something as long as it was consistant on being just 3 strings, but some may be more or less.
Any help would be extremely appreciated.
It's actually much easier than splitting strings into keys. Apples Key-Value-Coding allows exactly what you want.
[myDictionary valueForKeyPath:#"activity.message.status"];
A key path is a string of dot separated keys that is used to specify a sequence of object properties to traverse. The property of the first key in the sequence is relative to the receiver, and each subsequent key is evaluated relative to the value of the previous property.
For example, the key path address.street would get the value of the address property from the receiving object, and then determine the street property relative to the address object.
Key-Value Coding Programming Guide
You would do something like,
NSArray *array = [#"activity.message.status" componentsSeperatedByString:#"."];
Which will create an array containing {activity,message,status).
Now you have your array you can use for querying your dictionary.
[[[myDictionary objectForKey:[array objectAtIndex:0]] objectForKey:[array objectAtIndex:1]] objectForKey:[array objectAtIndex:2]];
Which is equivalent to:
[[[myDictionary objectForKey:#"activity"] objectForKey:#"message"] objectForKey:#"status"];
Hope this helps !
It's not clear to me from your question how we should map user1 to activity.message.status. For now I'll assume you mean that the template might contain a string like "{{activity.message.status}}" and you want to be able to parse that.
Here's one iteration that operates on an NSMutableString that can be looped until no match is found:
NSError *error = NULL;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:#"\\{\\{.+?\\}\\}"
options:NSRegularExpressionCaseInsensitive
error:&error];
NSRange matchRange = [regex rangeOfFirstMatchInString:string
options:0 range:NSMakeRange(0, [string length])];
NSRange keyPathRange = NSMakeRange(matchRange.location + 2, matchRange.length - 4);
NSString *keyPath = [string substringWithRange:keyPathRange];
NSString *newSubstring = [myDictionary valueForKeyPath:keyPath];
[string replaceCharactersInRange:matchRange withString:newSubstring];
I haven't tested this code.
How about a (recursive ... cool) category method on NSMutableDictionary like this:
- (void)setObject:(id)object forCompoundKey:(NSString *)compoundKey {
NSArray *keys = [compoundKey componentsSeparatedByString:#"."];
if ([keys count] == 1) {
return [self setObject:object forKey:compoundKey];
}
// get the first component of the key
NSString *key = [keys objectAtIndex:0];
// build the remaining key with the remaining components
NSRange nextKeyRange;
nextKeyRange.location = 1;
nextKeyRange.length = [keys count] - 1;
NSArray nextKeys = [keys subarrayWithRange:nextRange];
NSString *nextKey = [nextKeys componentsJoinedByString:#"."];
NSMutableDictionary *nextDictionary = [NSMutableDictionary dictionary];
[self addObject:nextDictionary forKey:key];
// now the cool part... recursion
[nextDictionary setObject:object forCompoundKey:nextKey];
}
I haven't tested this, but it passes a quick desk check. The objectForCompoundKey: retrieval can be written analogously.
Related
I'm making an iPhone app which displays information about red wines. The wines are stored in a plist containing an array of dictionaries. I'm adding a search view controller to the application, and to start up easy I want to get the wines who the value for the "Name" key contains nameString (from textbox).
It kind of stops here, I need some advices about the most suitable way of doing this. Is there a function in the NSArray class which will do the job, should bring in NSPredicate, NSUserDefaults, or are there other options? I've done some research but I'm going to need some advices and maybe an example to get started.
I will advance the search function to let the user include/exclude countries, get wines that suit this and that food, set minimum price, maximum price, and so on. The dictionaries have strings for all this info. So before I start on something advanced like this I'll need some advice for which functions could do my job the best.
-(IBAction)searchButtonPoke:(id)sender{
NSString *path = [[NSBundle mainBundle] pathForResource:#"Wines" ofType:#"plist"];
allObjectsArray = [[NSMutableArray alloc] initWithContentsOfFile:path];
NSString *nameString = [NSString stringWithFormat:#"%#", [nameTextField text]];
resultObjectsArray = /*objects where the value for the key "Name" contains
nameString*/;
How about simply iterating through the array and compare the names?
resultObjectsArray = [NSMutableArray array];
for(NSDictionary *wine in allObjectsArray)
{
NSString *wineName = [wine objectForKey:#"Name"];
NSRange range = [wineName rangeOfString:nameString options:NSCaseInsensitiveSearch];
if(range.location != NSNotFound)
[resultObjectsArray addObject:wine];
}
Swift version is even simpler:
let resultObjectsArray = allObjectsArray.filter{
($0["Name"] as! String).range(of: nameString,
options: .caseInsensitive,
range: nil,
locale: nil) != nil
}
Cheers,
anka
This Works !!! tested !!!
for (NSDictionary* dict in Array) {
if ([[dict objectForKey:#"key"] isEqualToString:string]) {
Index = [Array indexOfObject:dict];
}
}
We can use NSPredicate too, like this:
NSPredicate *predicate =
[NSPredicate predicateWithFormat:#"publisher == %#", #"Apress" ];
NSArray *filtered = [bookshelf filteredArrayUsingPredicate:predicate];
If the publisher can be found in the bookshelf array, filtered count will be bigger than 0.
I thinks this way is much cleaner way to search. Hope it helps.
remember to break; out your for loop once your object has been found
Currently I'm programming an app with a tableView, similar to that one in the iPhone Contacts app.
Everything works (the sections, the bar on the right showing the titles, the cells are configured...), beside the search bar. I'm familiar how to do this (search) if the tableView's data is loaded from an array, but my situation is that its loaded from arrays located in a NSDictionary.
The dict looks like
Key = "A" >> Value = "array = apple, animal, alphabet, abc ..."
Key = "B" >> Value = "array = bat, ball, banana ..."
How can I remove all strings (from all of the dictionary's arrays) matching the search term?
Thanks a lot in advance :)
Well you can do it like this
NSMutableDictionary *newItems = [NSMutableDictionary dictionary];
for (NSString *key in oldItems) {
NSMutableArray *newArray = [NSMutableArray array];
for (NSString *item in [oldItems objectForKey:key]) {
if ([item rangeOfString:searchTerm].location != NSNotFound) {
[newArray addObject:item];
}
}
if ([newArray count]) {
[newItems setObject:newArray forKey:key];
}
}
[oldItems release];
oldItems = [newItems retain];
I don't know if this is the best way to do it or even if it's faster enough but let me know if this works for you.
Did you want to update the existing Dictionary with the new Array that excludes that string?
NSMutableDictionary* excludedDictionary = [NSMutableDictionary dictionaryWithDictionary:existingDictionary];
for(id key in [existingDictionary allKeys])
{
NSArray* existingArray = [existingDictionary objectForKey:key];
NSPredicate* predicate = [NSPredicate predicateWithFormat:#"self != %#", excludedString];
NSArray* excludedArray = [existingArray filteredArrayUsingPredicate:predicate];
[excludedDictionary setObject:excludedArray forKey:key];
}
existingDictionary = [NSDictionary dictionaryWithDictionary:excludedDictionary];
This will replace your existing dictionary with one that doesn't have the string in it...
From you comments, I understand that you want to filter the table contents on the basis of what the user enters in the text field. For this, you do not need to modify your dictionary at every character change. The UISearchDisplayController is provided for exactly this scenario. Have a look at the reference for details: http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UISearchDisplayController_Class/Reference/Reference.html.
HTH,
Akshay
//COPY THIS CODE IN A FRESH PROJECT!!!
//THIS 2 LINES ARE JUST EXAMPLES, OF VALUES PUSHES OUT A DATABASE
NSString *messagelevel1 = #"45";
NSString *currentlevel = #"1";
NSString *HuidigLevel = currentlevel;
NSDecimalNumber *huidigleveldec = [[NSDecimalNumber alloc] initWithString: HuidigLevel];
float HuidigLevelRek = [huidigleveldec floatValue];
//HERE IS THE PROBLEM
NSString* LevelTotaal=[[NSString alloc] initWithFormat:#"messagelevel%.f",HuidigLevelRek];
NSString*result = LevelTotaal;
NSLog(#"%#",result);
// THE ABOVE RESULT SHOULD RETURN THE SAME VALUE AS THE NEXT (messagelevel1) LINE BUT IT RETURNS ONLY "messagelevel1" AND NOT THE VALUE!
NSLog(#"%#",messagelevel1);
I want the *result string behaves like the *huidiglevel string and fetch some information, but because the LevelTotaal is a NSString, It doesn't fetch this information. I really got no idea where to google for this problem, searching the Developer docs didn't helped either . Maybe you guys can help me out?
Actually the second NSLog returns the value and to first NSLog just returns messagelevel1. To tell you in short ;)
I hope you guys get what I'm saying!
I think what you're trying to do is use variable variables, a system that does not exist in Objective-C. In PHP, you can use variable variables:
$hello = 'abcdef';
$varName = 'hello';
print $$varName; // prints the value of $hello, which is 'abcdef'
Like many things in PHP, this is not really a good way to design software. Instead, consider using something like a NSDictionary, this allows you to give specific data a key.
NSMutableDictionary *aDict = [NSMutableDictionary dictionary];
[aDict setObject:[NSNumber numberWithFloat:4.5] forKey:#"messageLevel1"];
NSString *result = [aDict objectForKey:#"messageLevel1"];
You can obtain the data dynamically, the key can be generated or obtained at runtime.
Edit:
Rather than having variables called messageLevel1, messageLevel2, messageLevel3 ... messageLeveln, just use an array.
NSMutableArray *messageLevels = [NSMutableArray array];
[messageLevels addObject:#"1"];
[messageLevels addObject:#"45"];
[messageLevels addObject:#"123"];
NSString *result = [messageLevels objectAtIndex:HuidigLevelRek];
NSDictionary *story = [stories objectAtIndex: indexPath.row];
cell.text=[NSString stringwithFormat:[story objectForKey#"message];
i dont knw what exaclty "message " contains (what is the meaning of objectForKey#"message")
EDIT CODE
NSString *key =[appDelegate.books objectAtIndex:indexPath.row];
//dict y=#"Name";
NSArray *nameSection = [dict objectForKey:key];
NSDictionary *story = [nameSection objectAtIndex: indexPath.row];
cell.text=[NSString stringwithFormat:[story objectForKey:key]];
NSLog(#"Value Of message: %#", [dict objectForKey:key]);
why my code crashes
If you are more familiar with Java or C# the code is equivalent to something like this:
// Assuming stories is declared as: List<Dictionary<string, string> stories;
Dictionary<string, string> story = stories[indexPath.row];
cell.Text = String.Format(story["message"]);
In Smalltalk-style (and therefore Objective-C too) Object Oriented programming, methods are more like messages to other objects. So a good Objective-C method name should read like an English sentence (Subject-Verb-Object). Because of this working with dictionaries (hash tables) looks like this:
[myDictionary setObject:#"Value" forKey:#"someKey"];
[myDictionary objectForKey:#"someKey"]; // == #"Value"
In Java it would be:
myDictionary.put("someKey", "Value");
myDictionary.get("someKey"); // == "Value"
Notice how the key ("someKey") was the first argument in the Java example. In Objective-C you name your arguments with the method name, hence setObject: forKey:. Also notice that in Objective-C strings start with an # symbol. That's because Objective-C strings are different from regular C strings. When using Objective-C you almost always use Objective-C's # strings.
In C# there is a special syntax for Dictionaries so it becomes:
myDictionary["someKey"] = "Value";
myDictionary["someKey"]; // == "Value"
One important problem that you might encounter if you're new is the problem of native types.
In Java to add an int to a Dictionary you used to have to do:
myDictionary.put("someKey", new Integer(10));
Because the primitive types (int, char/short, byte, boolean) aren't real Objects. Objective-C has this problem too. So if you want to put an int into a dictionary you must use NSNumber like so:
[myDictionary setObject:[NSNumber numberForInt:10]
forKey:#"someKey"];
And you pull out the integer like so:
NSNumber *number = [myDictionary objectForKey:#"someKey"];
[number intValue]; // == 10
EDIT:
Your code might be crashing if you have a '%' character in your string, since stringWithFormat is just like NSLog in that it takes many arguments. So if story["message"] is "Hello" then it'll work fine without extra arguments but if it's "Hello %#" you need to add one argument to stringWithFormat.
NSString *message = #"Hello %#";
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
[dict setObject:message forKey:#"message"];
NSString *output = [NSString stringWithFormat:[dict objectForKey:#"message"], #"World!"];
// output is now #"Hello World!".
#"message" is a key for a value stored in the NSDictionary object. The first line declares an NSDictionary named story that appears to come from an array.
If you want to find what value is stored for the key:#"message", consider using:
NSLog(#"Value Of message: %#", cell.text);
Run and check the console to see the output. (SHIFT + COMMAND + Y) in XCode will bring up the console, if that's what you are using. If you are unfamiliar with NSArrays/NSDictionaries, give Apple's Documentation a look.
I'm just guessing at all of this since that is a very limited sample of code. Try submit more code when you ask a question so that the viewers can get a better idea of your questions.
That is an example of key-value coding, and a lot of information is available on the Apple dev site if you're interested:
http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/KeyValueCoding/KeyValueCoding.html
I have an array of NSDictionaries. How can I pull out the first element in the dictionary?
NSArray *messages = [[results objectForKey:#"messages"] valueForKey:#"message"];
for (NSDictionary *message in messages)
{
STObject *mySTObject = [[STObject alloc] init];
mySTObject.stID = [message valueForKey:#"id"];
stID = mySTObject.stID;
}
There is no "first" element in an NSDictionary; its members have no guaranteed order. If you just want one object from a dictionary, but don't care which key it's associated with, you can do:
id val = nil;
NSArray *values = [yourDict allValues];
if ([values count] != 0)
val = [values objectAtIndex:0];
NSDictionaries are unordered, meaning that there are not first or last element. In fact, the order of the keys are never guaranteed to be the same, even in the lifetime of a specific dictionary.
If you want any object, you can get one of the keys:
id key = [[message allKeys] objectAtIndex:0]; // Assumes 'message' is not empty
id object = [message objectForKey:key];
NSArray has a selector named firstObject that simplifies the code and makes it more readable:
id val = [[yourDict allValues] firstObject];
If yourDict is empty val will be nil, so is not necessary to check the dictionary/array size.
Simplest:
[[dict objectEnumerator] nextObject];
According to Apple, calls to allKeys or allValues incur the cost of creating new arrays:
A new array containing the dictionary’s values, or an empty array if
the dictionary has no entries (read-only)
So, an alternative option that does not incur such cost could look like this:
NSString* key = nil;
for(key in yourDict)
{ // this loop will not execute if the dictionary is empty
break; // exit loop as soon as we enter it (key will be set to some key)
}
id object = yourDict[key]; // get object associated with key. nil if key doesn't exist.
Note: If the dictionary is empty, the key will remain nil, and the object returned will also be nil, we therefore don't need special handling of the case where the dictionary is actually empty.
If someone is still looking for answer for this type of situation then can refer this:
// dict is NSDictionary
// [dict allKeys] will give all the keys in dict present
// [[dict allKeys]objectAtIndex:0] will give from all the keys object at index 0 because [dict allKeys] returns an array.
[[dict allKeys]objectAtIndex:0];
If you have NSDictionary named message,
It's pretty simple:
message[[[message allKeys] objectAtIndex:0]];
But you have to be sure (or better check) that your dictionary has at least one element.
Here is how you can check it:
if ([message allKeys] > 0) NSLog(#"%#", message[[[message allKeys] objectAtIndex:0]]);
But NSDictionary has no guaranteed order, so you probably should use this code only if your dictionary has only one element.
[UPDATE]
It's also good idea to use this if you need to get ANY element of dictionary
Try this:
NSDictionary *firstValue = [responseObject objectAtIndex:0];