I know there are a whole bunch of questions that have been asked and answered in stackoverflow about the challenge of getting keys in an NSDictionary sorted by putting those keys into sort order in an array. I understand that objects are not stored in sort order within the actual dictionary and that is, I think, for reasons of efficiency or maybe memory management on the part of Foundation code.
I have been working on trying out examples from several answers out here and in apple documentation and blogs (some I can get to work, others not!) , but I can't seem to find an example that solves my confusion.
I think my confusion is that the examples I'm encountering both here, in apple documentation and in the different helpful blogs, all seem to have examples where there is just a key value pair and the second value is not an object - it's more like just a value. (However isn't it really an object at some level? I would think it is)
One example, that I couldn't get to work (Sorting an NSArray by an NSDictionary value ) , uses this idea
[array sortedArrayUsingComparator:^(NSDictionary *item1, NSDictionary *item2) {
NSString *age1 = [item1 objectForKey:#"age"];
NSString *age2 = [item2 objectForKey:#"age"];
return [age1 compare:age2 options:NSNumericSearch];
}];
I thought maybe this idea, specifying the key in a more specific manner, might be my problem.
I wonder if maybe I'm not communicating to the compiler what the key is, and what the object is, and that is why I'm getting an "unrecognized selector sent to instance" error.
..... Code Snips Follow .....
1)
I have a class called "Dog". A given dog object has several properties, including an NSString key.
My key is "licenseString" is an alphanumeric key - I'm also wondering if I should use decimalNumberWithString but that's not the question here
#property (strong,nonatomic) NSString *licenseString;
#property (strong, nonatomic) NSString *dogName;
#property (strong, nonatomic) NSString *whatMakesDogSpecial;
#property (strong, nonatomic) UIImage *dogPhoto;
2) I have an NSDictionary
#property (nonatomic, strong) NSDictionary *dogDictionary;
I hardcode information into the dogDictionary in this not very sophisticated way,
Dog *aDog;
// Dog one
aDog = [[Dog alloc]init] ;
aDog.licenseString = #"1";
aDog.dogName = #"Oscar";
aDog.whatMakesDogSpecial = #"This animal was found at the Mid-Penn humane society. He is super friendly, plays well with other dogs and likes people too. He enjoys fetching balls and frisbees too. He also goes to the park daily." ;
aDog.dogPhoto = [UIImage imageNamed:#"webVuMiniAppDogOscar.jpg"];
[self.dogDictionary setValue:aDog forKey:aDog.licenseString];
3) Then once I have several dog objects in my dogDictionary, I want to sort on the license tag values, so that I can populate a table view with dog names, but by order of their license tags.
BTW it seems that the compiler does recognize "vars.dogDictionary" which appears in the code snip below, because when I look at the debugger I can see that two valid instances are coming up from my dog dictionary. The debugger output is in an attachment
So, using ideas from a stackoverflow answer and the apple documentation, I write this
NSArray *sortedKeys = [vars.dogDictionary keysSortedByValueUsingComparator:
^NSComparisonResult(id obj1, id obj2) {
return [obj1 compare:obj2];
}];
NSLog(#" The sorted array is %#", sortedKeys);
And that's where my problem happens. I recognize that 0x1182f740 refers to "obj1" as shown in the debugger attachment
2013-08-06 15:13:58.276 SortDogLIcenseTags[3876:11303] -[Dog compare:]: unrecognized selector sent to instance 0x1182f740
(lldb)
Attachment is a picture showing debugger values - they don't like to paste very well
Here's how I resolved this challenge. It works and was pretty straightforward to integrate into my Master/Detail project
I know I found a tutorial on the web somewhere that led me to this solution , I'm sorry I can't find it now.
Note that sortedDogDictionaryArray and dogDictionaryArray are declared as properties in the .h file.
self.dogDictionaryArray = [vars.dogDictionary allValues];
// Sort
NSSortDescriptor *sortDescriptorDog =
[[NSSortDescriptor alloc] initWithKey:#"licenseString" ascending:YES];
NSArray *sortDescriptorsDogs =
[NSArray arrayWithObject:sortDescriptorDog];
self.sortedDogDictionaryArray =
[self.dogDictionaryArray sortedArrayUsingDescriptors:sortDescriptorsDogs];
NSLog(#"%#",self.sortedDogDictionaryArray );
int doggie;
Dog *someDogName;
NSLog(#"Sorted Order is...");
for (doggie = 0; doggie < [self.sortedDogDictionaryArray count]; doggie++) {
//NSLog(#"%#", [sortedArray objectAtIndex:i]);
//NSLog(#"%#", [sortedArrayDogs objectAtIndex:doggie]);
someDogName = [self.sortedDogDictionaryArray objectAtIndex:doggie];
//NSLog(#"name is %#", someDogName.dogName);
NSLog(#"name is %# tag is %#", someDogName.dogName, someDogName.licenseString);
}
Related
I would like to bind NSTableColumn's headerTitle property to an NSMutableArray in my model layer (via an NSArrayController).
Basically I want to have an array where I can change values and have the table column header titles update. Is that reasonable?
However, the headerTitle binding wants an single NSString and I'm not sure how to connect my model object to this binding via my NSArrayController. Google does not give many hits for this problem.
My model layer consists of two class (both of which are appropriately KVC compliant). The first is a model which represents a single column title, it has one property title,
// A model class representing the column title of single NSTableColumn
#interface ColumnTitle : NSObject
#property NSString *title;
+ (ColumnTitle*) columnTitleWithTitle:(NSString*) aString;
#end
The second a model object which represents an ordered group of ColumnTitle objects,
// Class representing an order collection of model items
#interface TableColumnTitles : NSObject
#property NSMutableArray* columnTitles; // an array of ColumnTitle objects
// These are the KVC array accessors
-(void) insertObject:(ColumnTitle*)columnTitle inColumnTitlesAtIndex:(NSUInteger)index;
- (void)removeObjectFromColumnTitlesAtIndex:(NSUInteger)index;
- (void)replaceObjectInColumnTitlesAtIndex:(NSUInteger)index withObject:(ColumnTitle*)columnTitle;
#end
Note that TableColumnTitles object implements the above array accessors which are required for the bindings. Any suggestions?
Haven't tried that before but what you're actually asking for is using KVC for array indexes. A quick google didn't turn up anything on that issue except some results that indicate it's not (yet) possible (check this)
The easiest work-around I could come up with would be to simply add dedicated properties for the array indexes.. not nice but does the job.
So for a NSMutableArray called myArray and contains objects with title properties of type NSString you'd do something like:
#property (nonatomic, readonly, getter = columnOneGetter) NSString *columnOneString;
(NSString*) columnOneGetter
{
return myArray[0].title;
}
Always assuming of course their number is known in advance and we're not talking 200 columns :-)
I think this may/may not be what you're after, but quick google search landed me here:
http://pinkstone.co.uk/how-to-add-touch-events-to-a-uitableviewfooter-or-header/
edit: i realize this is for mac (not ios) but should be pretty easy to translate if it actually helps.
I have an NSTableview which s bound to a NSArrayController. The Table/Arraycontroller contains Core Data "Person" entities. The people are added to the NSTableview by the GUI's user.
Let's say a person entity looks like
NSString* Name;
int Age;
NSString* HairColor;
Now I want to iterate over what is stored in the array controller to perform some operation in it. The actual operation I want to do isn't important I don't really want to get bogged down in what I am trying to do with the information. It's just iterating over everything held in the NSArraycontroller which is confusing me. I come from a C++ and C# background and am new to Cocoa. Let's say I want to build a NSMutableArray that contains each person from nsarraycontroller 1 year in the future.
So I would want to do something like
NSMutableArray* mutArray = [[NSMutableArray alloc] init];
foreach(PersonEntity p in myNsArrayController) // foreach doesn't exist in obj-c
{
Person* new_person = [[Person alloc] init];
[new_person setName:p.name];
[new_person setHairColor:p.HairColor];
[new_person setAge:(p.age + 1)];
[mutArray addObject:new_person];
}
I believe the only thing holding me back from doing something like the code above is that foreach does not exist in Obj-c. I just don't see how to iterate over the nsarraycontroller.
Note: This is for OSX so I have garbage collection turned on
You're looking for fast enumeration.
For your example, something like
for (PersonEntity *p in myNsArrayController.arrangedObjects)
{
// Rest of your code
}
You can also enumerate using blocks. For example:
[myNsArrayController enumerateObjectsUsingBlock:^(id object, NSUInteger index, BOOL *stop)
{
PersonEntity *p = object;
// Rest of your code
}];
There's pro's and cons to both approaches. These are discussed in depth in the answer to this question:
Objective-C enumerateUsingBlock vs fast enumeration?
You can find a great tutorial on blocks in Apple's WWDC 2010 videos. In that they say that at Apple they use blocks "all the time".
Ok this is third day of working with Xcode so please be nice.
I am trying to set up a simple table to display records from an existing sqlite database. I've got as far as loading the database into a NSMutableArray and have verified the size is correct, but I can't loop through it and get the data properly out. All that displays is the last record of the table.
Here is the sample code:
while([results next]) {
self.subject_id = [results stringForColumn:#"SUBJECT_ID"];
self.subject = [results stringForColumn:#"SUBJECT"];
self.category = [results stringForColumn:#"CATEGORY"];
[subjects addObject:self];
NSLog(#"AFTER record: %# - %# - %#", self.subject_id, self.subject, self.category);
}
As the loop prints out to the log I verify that the correct data is being looped through.
Then I run this immediately after populating the array and I get the same last entry, each time:
//PULL UP THE THINGY AND SEE IF IT WORKS
Subject *sub;
int x = 0;
for (sub in subjects){
Subject *xsub = [subjects objectAtIndex:x];
NSLog(#" %i sub data ------- %#, ----- %#", x, xsub.subject, xsub.category);
x = x+1;
};
sub = [subjects objectAtIndex:50];
NSLog(#" sub data ------- %#, ----- %#", sub.subject, sub.category);
I even tried specifically pulling up a record from the Array like this but I get the same last record instead of the record I asked for:
sub = [subjects objectAtIndex:50];
"Subject" is a class giving the field names of my table. I haven't used the entity feature yet.
My header file declares the field names like this:
#property (nonatomic, retain) NSString * subject_id;
#property (nonatomic, retain) NSString * subject;
#property (nonatomic, retain) NSString * category;
I used the FMDB wrapper to get the data from my database and pieced together the classes from a couple different tableView examples such as the Animals one.
Can anyone give me some direction on how to debug this?
My guess would be either that each array object has had the same text loaded into it, or that the same object has been added to the array multiple times.
Either way, I'd take a long hard look at the array loading code.
I was looking at NSTokenField, NSTextField and NSTextView with no luck to do the following:
I am writing a Twtitter client and when you want to twitter a new Tweet then you begin to write in a text field for example:
Going to make coffee, #pe
When you begin to write a # then I would like to help the user to autocomplete the username for example #peter. I have a NSArray with the usernames like:
NSArray *usernames = [NSArray arrayWithObjects:#"#andreas", #"#clara", #"#jeena", #"#peter"]
What should I do to enable a simple autocompletation? I'd be happy if you would have to press F5 or something for starters too. The problem I am having is that with NSTokenField I don't know how I should tokenize the string, with NSTextField it only works when I write the #username at the beginning of the tweet and NSTextView seems really complicated and too much for such a simple thing.
The most basic implementation involves overriding this method... Definitely not optimal, but you should get the idea:
- (NSArray *) completionsForPartialWordRange:(NSRange)charRange indexOfSelectedItem:(NSInteger *)index {
// this would be defined somewhere else, but just for example..
NSArray *usernames = [NSArray arrayWithObjects:#"#andreas", #"#clara", #"#jeena", #"#peter"];
NSMutableArray *matchedNames = [NSMutableArray array];
NSString *toMatch = [[self string] substringWithRange:charRange];
for(NSString *username in usernames) {
[matchedNames addObject:username];
}
return matchedNames; // that's it.
}
Once you start having a lot of data, you'll need to employ strategies to pre-do your searches by storing words into hashes with the partial pieces of text in them (like, "Hello" would be put into 4 different arrays stuff into NSDictionary keys for "H", "He", "Hel", "Hell" .. Repeat with every word in your Lexicon. Much quicker that way.
If you want to support auto-complete, just call the 'complete:' method when you detect text is changing in your control.
I have an NSMutableArray i am trying to convert into a string.
Declaring my NSMutableArray...
NSMutableArray *listData;
And later inside a method...
NSString *foo = [listData componentsJoinedByString:#"|"];
NSLog(#"%#",foo);
It seems no matter what i try i keep getting EXC_BAD_ACCESS.
To make sure each element in my array was an NSString i also tried this...
NSMutableArray *mArray = [[NSMutableArray alloc] init];
for (id ln in listData) {
NSString *boo = [NSString stringWithFormat: #"%#",ln];
[mArray addObject:boo];
}
NSString *foo = [mArray componentsJoinedByString:#"|"];
NSLog(#"%#",foo);
I can manipulate my NSMutableArray by adding/deleting objects in the same method or other methods inside my class. But when i try "componentsJoinedByString" the error pops up. Does anyone have any advice or another way i can combine this array into a single NSString?
In the code you've given, there will never be an NSMutableArray for listData. At some point in your code, you'll need to create one, and presumably populate it.
Edit
Okay, so you may get into memory management problems here, so let's be a bit clearer:
You're synthesizing getters and setters for the instance variable, so it's good practice to use those to access it, they'll take care of retain and releasing appropriately.
To set listData you can simply use
self.listData = [listManage getList:[[NSUserDefaults standardUserDefaults] stringForKey:#"list_name"] list:#"LIST"];
or
[self setListData:[listManage getList:[[NSUserDefaults standardUserDefaults] stringForKey:#"list_name"] list:#"LIST"]];
if you prefer.