I want store a URL against a UILabel so that when a user touches the label it takes them to that URL in a UIWebView.
I have declared a NSDictionary like so:
NSMutableArray *linksArray = [[NSMutableArray alloc] init];
[linksArray addObject: [NSValue valueWithNonretainedObject: newsItem1ReadMoreLabel]];
[linksArray addObject: [NSValue valueWithNonretainedObject: newsItem2ReadMoreLabel]];
[linksArray addObject: [NSValue valueWithNonretainedObject: newsItem3ReadMoreLabel]];
[linksArray addObject: [NSValue valueWithNonretainedObject: newsItem4ReadMoreLabel]];
[linksArray addObject: [NSValue valueWithNonretainedObject: newsItem5ReadMoreLabel]];
//NSString *ageLink = #"http://www.theage.com.au";
NSArray *defaultLinks = [NSArray arrayWithObjects: #"1", #"2", #"3", #"4", #"5", nil];
self.urlToLinkDictionary = [[NSMutableDictionary alloc] init];
self.urlToLinkDictionary = [NSDictionary dictionaryWithObjects:defaultLinks forKeys:linksArray];
Considering I used a NSValue as the key, how do I get/set the URL associated with that key given that I only have references to the UILabels?
this is what I have but it doesn't work:
for(NSValue *key in [self.urlToLinkDictionary allKeys])
{
if ([key nonretainedObjectValue] == linkedLabel)
{
[self.urlToLinkDictionary setValue:[newsItem link] forKey: key];
}
}
but I get an error: "objc_exception_throw" resolved
These two lines are the cause of the issue:
self.urlToLinkDictionary = [[NSMutableDictionary alloc] init];
self.urlToLinkDictionary = [NSDictionary dictionaryWithObjects:defaultLinks forKeys:linksArray];
First you assign a mutable array to the property. Then you assign a different immutable array to the property. Your original mutable array leaks because you don't release it.
The exception is being caused by this line:
[self.urlToLinkDictionary setValue:[newsItem link] forKey: key];
By the time you get to it, self.urlToLinkDictionary is an immutable dictionary. You can't change it.
There are other problems:
linksArray leaks because you never release it.
newsItem1ReadMoreLabel etc. What type are they? Why are you wrapping them in values?
setValue:forKey: is part of key value coding. On a mutable dictionary it works, but the correct method for accessing objects by keys is setObject:forKey:
it seems a bit pointless to search a dictionary by doing a linear search through its keys.
Why not try a more simplified approach. Associate a tag with every label. The tag is a in integer value and you can use it to locate the url in an array.
So code for creating the array.
NSMutableArray* arrayURLs = [NSMutableArray arrayWithCapacity:2];
newsItem1ReadMoreLabel.tag = 0;
[arrayURLs insertObject:urlStringforLabel1 atIndex:newsItem1ReadMoreLabel.tag];
newsItem2ReadMoreLabel.tag = 1;
[arrayURLs insertObject:urlStringforLabel2 atIndex:newsItem2ReadMoreLabel.tag];
then you can access the urlstring for the appropriate label
NSString* url = [arrayURLs objectAtIndex:labelClicked.tag];
Related
I am trying to retrieve the values from my NSDictionary however I am running into errors, I was wondering if someone might be able to help me with my solution.
I have 18 values, not all are shown here that I am checking, when the correct key is reached I would like to take the value in the NSDictionary and pass it into one of my NSString variables.
Below is an example of what I am trying to do however like I say I am having several issues
for (id key in searchData) {
if ([[searchData objectForKey:key] isEqualToString:#"Code"]) {
codeSeries = [searchData objectForKey:key];
}
else if ([[searchData objectForKey:key] isEqualToString:#"ID"]) {
IDSeries = [searchData objectForKey:key];
}
// ...
However, when I try to log out any of the values, they all return Null. I have checked the dictionary before hand and the values are all most definitely in there, so I am thinking there is something wrong with my code above.
Any help would be greatly appreciated.
Update
This is how I create the NSDictionary
//start of mymethod...
NSDictionary *sendSeriesDictionary = [[NSDictionary alloc] init];
// Keys for sendSeriesDictionary
NSArray *keys = [NSArray arrayWithObjects:#"Code", #"ID", nil];
// Objects for keys that are for sendSeriesDictionary
NSArray *objects = [NSArray arrayWithObjects: [NSNull null], IdString, nil];
// Add keys and objects to NSDictionary
sendSeriesDictionary = [NSDictionary dictionaryWithObjects:objects forKeys:keys];
[engineRequests SeriesSearch:sendSeriesDictionary]; // this is where I send the NSDictionary over to where I want to read it.
//end of mymethod
You've got several problems. First, you mix up keys and values (like Tom said). Second, you have a possible memory leak where you create the dictionary, or at least a unnecessary instantiation.
Try this for creating the dictionary:
// Keys for sendSeriesDictionary
NSArray *keys = [NSArray arrayWithObjects:#"Code", #"ID", nil];
// Objects for keys that are for sendSeriesDictionary
NSArray *objects = [NSArray arrayWithObjects: [NSNull null], IdString, nil];
// Add keys and objects to NSDictionary
NSDictionary *sendSeriesDictionary = [NSDictionary dictionaryWithObjects:objects forKeys:keys];
Retrieving the values can be done like this:
codeSeries = [searchData objectForKey:#"Code"];
IDSeries = [searchData objectForKey:#"ID"];
In your first loop you looped through all the keys, got their values and then compared those to the key again. Which makes no sense.
Are you mixing keys and values ?
Maybe you just want codeSeries = [searchData objectForKey:#"Code"]; ?
I'm try to use the functions -setValue:forKey: and get the value using -valueForKey:
Example:
NSArray *rootarr = [[NSArray alloc] init];
NSArray *array = [[NSArray alloc] initWithObjects:#"name", #"address", #"title", nil];
[rootarr setValue:array forKey:#"n"];
NSArray *getArr = [rootarr valueForKey:#"n"];
But the getArr array I got is not equal the array I set (array).
Could you please tell me what's wrong I met. And what's the way to use these functions?
NSArray's setValue:forKey: method is used for Key Value Coding, not for using an array as an associative container. You need to use NSMutableDictionary.
NSMutableDictionary *rootDict = [NSMutableDictionary dictionary];
NSArray *array = [[NSArray alloc] initWithObjects:#"name", #"address", #"title", nil];
[rootDict setValue:array forKey:#"n"];
NSArray *getArr = [rootDict valueForKey:#"n"];
An array isn't a key-value store, which you appear to want to use it as. I think you want an NSDictionary instead (or more precisely NSMutableDictionary if you want to modify it after its created).
According to the Apple documentation setValue:forKey:
Invokes setValue:forKey: on each of the array's items using the specified value and key.
Practical uses are when you want to set the same value to each element of the array
UILabel *label1 = [[UILabel alloc]init];
UILabel *label2 = [[UILabel alloc]init];
NSArray *arr = #[label1, label2];
[arr setValue:#"bye" forKey:#"text"];
NSLog(#"%# %#",label1.text, label2.text); // bye bye
in your example "getArr" is an empty array because your "rootarr" doesn't have elements, otherwise you receive a setValue:forUndefinedKey: into the contained objects that are not compliant for the assigned key
You can't add objects to an NSArray after it is created. You have to use NSMutableArray in order to do that.
So I have an array of NSDictionaries, each NSDictionary has a bunch of key/value pairs pertaining to aspects of a photo (from Flickr).
I'm making an app that has a UITableViewController whose cells should be each of the different categories of the photos. So in pseudocode, I'm trying to construct a new NSDictionary (with keys being categories of photos, values being the NSDictionaries of the photos that contains that key). I'm iterating through each NSDictionary in the initial array, getting the category tags, and saying, if my new NSDict doesn't contain this key, make a new key to an empty array. Then add the current NSDict to that array. I'm getting consistent errors, not sure why.
Here's the diluted code.
photoList = [FlickrFetcher photosWithTags:[NSArray arrayWithObjects: #"CS193p_SPoT", nil]];
NSLog(#"%#", photoList);
categories = [[NSDictionary alloc] init];
NSArray *temp = [[NSArray alloc] init];
for (id obj in photoList) {
temp = [[obj objectForKey:#"tags"] componentsSeparatedByString:#" "];
for (id string in temp) {
if (![categories objectForKey:string]) {
NSMutableArray *arr = [[NSMutableArray alloc] init];
[categories setObject:arr forKey:string];
//[arr release];
}
NSMutableArray *photos = [categories objectForKey:string];
[photos addObject:obj];
[categories setObject:photos forKey:string];
}
}
Thanks!
NSDictionary doesn't have a method setObject:forKey:. You need an NSMutableDictionary.
self.categories = [NSMutableDictionary dictionary];
Other than that, please do use Joost's excellent rewrite of your code.
SIGABRT, just so you know, most likely means that an assertion somewhere failed. In this case, it may be an assertion all the way down in CoreFoundation*; CF checks for mutability when you try to access a dictionary like that and causes an interrupt if the object isn't mutable.
*I have just learned about the CF source's availability recently and have been looking through it, so this may be just "new thing" bias and incorrect.
I don't notice any errors (syntax-errors, that is) in your code, however here is an updated piece of code which has been implemented a bit cleaner (and without memory leaks)
self.photoList = [FlickrFetcher photosWithTags:[NSArray arrayWithObjects: #"CS193p_SPoT", nil]];
NSLog(#"%#", photoList);
self.categories = [NSDictionary dictionary];
for (NSDictionary *obj in photoList) {
NSArray *temp = [[obj objectForKey:#"tags"] componentsSeparatedByString:#" "];
for (NSString *string in temp) {
NSMutableArray *photos = [categories objectForKey:string];
if (!photos) {
photos = [NSMutableArray array];
[categories setObject:photos forKey:string];
}
[photos addObject:obj];
}
}
If it's not working please tell us the exact warning, and were it is caused.
I have a simple code:
NSMutableArray *arrayCheckList = [[NSMutableArray alloc] init];
[arrayCheckList addObject:[NSMutableDictionary dictionaryWithObjects:[NSArray arrayWithObjects:#"2011-03-14 10:25:59 +0000",#"Exercise at least 30mins/day",#"1",nil] forKeys:[NSArray arrayWithObjects:#"date",#"checkListData",#"status",nil]] ];
[arrayCheckList addObject:[NSMutableDictionary dictionaryWithObjects:[NSArray arrayWithObjects:#"2011-03-14 10:25:59 +0000",#"Take regular insulin shots",#"1",nil] forKeys:[NSArray arrayWithObjects:#"date",#"checkListData",#"status",nil]]];
Now I want to add a specific index of above array to a dictionary. Below are two way, which one is better and why? What are the specific drawbacks of the latter?
NSDictionary *tempDict = [[NSDictionary alloc] initWithDictionary:[arrayCheckList objectAtIndex:1]];
OR
NSDictionary *tempDict = [arrayCheckList objectAtIndex:1];
What would the impact on the latter since I am not doing any alloc/init in it?
1:
NSDictionary *tempDict = [[NSDictionary alloc] initWithDictionary:[arrayCheckList objectAtIndex:1]];
Creates a new immutable dictionary object as a copy of the original one. If you add objects to the mutable dictionary in your arrayCheckList they will not be added to your copied reference.
2:
NSDictionary *tempDict = [arrayCheckList objectAtIndex:1];
This directly pulls the mutable dictionary from your array and not a copy. The following two lines will be equivalent:
[[arrayCheckList objectAtIndex:1] addObject:something];
[tempDict addObject:something];
The first one potentially copies the dictionary a index 1 of the array. (It should, since you're creating an immutable dictionary but the one in the array is mutable.) The second only gets a reference to the dictionary in the array -- there's no chance of creating a new object.
I want to programatically create a dictionary which feeds data to my UITableView but I'm having a hard time with it. I want to create a dictionary that resembles this property list (image) give or take a couple of items.
I've looked at "Property List Programming Guide: Creating Property Lists Programmatically" and I came up with a small sample of my own:
//keys
NSArray *Childs = [NSArray arrayWithObjects:#"testerbet", nil];
NSArray *Children = [NSArray arrayWithObjects:#"Children", nil];
NSArray *Keys = [NSArray arrayWithObjects:#"Rows", nil];
NSArray *Title = [NSArray arrayWithObjects:#"Title", nil];
//strings
NSString *Titles = #"mmm training";
//dictionary
NSDictionary *item1 = [NSDictionary dictionaryWithObject:Childs, Titles forKey:Children , Title];
NSDictionary *item2 = [NSDictionary dictionaryWithObject:Childs, Titles forKey:Children , Title];
NSDictionary *item3 = [NSDictionary dictionaryWithObject:Childs, Titles forKey:Children , Title];
NSArray *Rows = [NSArray arrayWithObjects: item1, item2, item3, nil];
NSDictionary *Root = [NSDictionary dictionaryWithObject:Rows forKey:Keys];
// NSDictionary *tempDict = [[NSDictionary alloc] //initWithContentsOfFile:DataPath];
NSDictionary *tempDict = [[NSDictionary alloc] initWithDictionary: Root];
I'm trying to use this data of hierachy for my table views.
So I was wondering how can I can create my property list (dictionary) programmatically so that I can fill it with my own arrays.
I'm still new with iPhone development so bear with me. ;)
This is a situation where "teach a man to fish" is a vastly more helpful approach than "give a man a fish". Once you understand the basic principles and the NSDictionary API, it becomes much easier to craft your own custom solution. Here are a few observations and learning points:
The method +dictionaryWithObject:forKey: is used to create an NSDictionary with a single key-value pair. It will not accept comma-separated arguments after each colon (:) in the method call, just one. To create a dictionary with multiple key-value pairs, use one of 2 related methods: +dictionaryWithObjects:forKeys: which accepts two NSArray objects containing values and keys, or +dictionaryWithObjectsAndKeys: which alternates (object, key, object, key) with a terminating nil argument.
Simplify the creation code. You don't need a million local variables just to create the thing. Use inline arguments where it makes sense. One way to do this it to build up your dictionary in code as an NSMutableDictionary, then (if necessary) make an immutable copy of it by calling -copy on it. (Remember that a copy method returns a new object that you must release to avoid memory leaks.) That way you don't have to have a variable for every single value so you can do a "one shot" creation of the structure(s) at each level.
Use +arrayWithObject: for creating an NSArray with a single object.
(Style suggestions) Never use an uppercase letter to begin the name of a variable, method, or function. (Notice that SO highlights leading-caps variables like class names.) It will certainly help others who read your code from being confused about your intent by your naming scheme.
Just to give you a flavor of what creating the dictionary in the linked image might look like in code... (I'm ignoring your chosen variable names and using both different approaches for completeness.)
NSDictionary *item1 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:#"Screen J",[NSNumber numberWithInt:3],nil]
forKeys:[NSArray arrayWithObjects:#"Title",#"View",nil]];
NSDictionary *item2 = [NSDictionary dictionaryWithObjectsAndKeys:
#"Screen I", #"Title",
[NSArray arrayWithObject:item1], #"Children",
nil];
...
I am not sure I understand the basic objective here.
It seems like at runtime, you are constructing a deep dictionary with many child nodes. But you are constructing this all with static code... why can you not simply make a plist (like the one you had an image of) and read that into an NSDictionary? Both NSDictionary and NSArray have methods that let you simply read in a file and get a whole filled out object. Then it is WAY easier to edit and to understand. That method is dictionaryWithContentsOfFile.
If all of the data is truly created at runtime before it is put into the dictionary, then it seems like you would want a very different, recursive, style of code rather than the flat examples given.
Lastly, I personally dislike the dictionaryWithObjects:forKeys: method in NSDictionary for building a dictionary. If you have to do things that way I greatly prefer the alternate method dictionaryWithObjectsAndKeys: which does the same thing but keeps the keys with the objects:
NSDictionary *item1 = [NSDictionary dictionaryWithObjectsAndKeys:
#"Screen J",
#"Title",
[NSNumber numberWithInt:3],
#"View"];
NSMutableDictionary *topLevel = [NSMutableDictionary dictionary];
NSMutableDictionary *item1 = [NSMutableDictionary dictionary];
NSString *item1title = [NSString stringWithString:#"Title 1"];
NSMutableDictionary *item1children = [NSMutableDictionary dictionary];
// create children
NSString *item1child1 = [NSString stringWithString:#"item 1, child 1"];
NSMutableDictionary *item1child2 = [NSMutableDictionary dictionary];
NSString *item1child2title = [NSString stringWithString:#"Title 1-2"];
NSMutableDictionary *item1child2children = [NSMutableDictionary dictionary];
NSString *item1child2child1 = [NSString stringWithString:#"item 1, child 2, child 1"];
NSString *item1child2child2 = [NSString stringWithString:#"item 1, child 2, child 2"];
[item1child2 setObject:item1child2title forKey:#"Title"];
[item1child2children setObject:item1child2child1 forKey:#"item 1 child2 child 1"];
[item1child2children setObject:item1child2child2 forKey:#"item 1 child2 child 2"];
[item1child2 setObject:item1child2children forKey:#"children"];
// add children to dictionary
[item1children setObject:item1child1 forKey:#"item1 child1"];
[item1children setObject:item1child2 forKey:#"item1 child2"];
// add to item 1 dict
[item1 setObject:item1title forKey:#"Title"];
[item1 setObject:item1children forKey:#"children"];
NSMutableDictionary *item2 = [NSMutableDictionary dictionary];
NSString *item2title = [NSString stringWithString:#"Title"];
NSMutableDictionary *item2children = [NSMutableDictionary dictionary];
NSString *item2child1 = [NSString stringWithString:#"item 2, child 1"];
NSString *item2child2 = [NSString stringWithString:#"item 2, child 2"];
NSString *item2child3 = [NSString stringWithString:#"item 2, child 3"];
// add children to dictionary
[item2children setObject:item2child1 forKey:#"item2 child1"];
[item2children setObject:item2child2 forKey:#"item2 child2"];
[item2children setObject:item2child3 forKey:#"item2 child3"];
// add to item 2 dict
[item2 setObject:item2title forKey:#"Title"];
[item2 setObject:item2children forKey:#"children"];
[topLevel setObject:item1 forKey:#"Item 1"];
[topLevel setObject:item2 forKey:#"Item 2"];
first of .. super! thanks .. I really appreciate the explanation and code snippet.
Since you gave me such a good explanation I hope you don't mind me asking a couple more questions.
First, I did as you suggested and this is what I came up with :
(I used my original property list instead of the example this time so this is where the drilldown table gets his( or needs to get his ) treestructure).
http://img509.imageshack.us/img509/7523/picture2lsg.png
NSDictionary *root = [NSMutableDictionary dictionary];
NSDictionary *item1 = [NSDictionary dictionaryWithObject:[NSArray arrayWithObject:#"VirtuaGym Online"] forKey:[NSArray arrayWithObjects:#"Title"]];
NSDictionary *item2 = [NSDictionary dictionaryWithObject:[NSArray arrayWithObject:#"Do the training"] forKey:[NSArray arrayWithObjects:#"Title"]];
NSDictionary *item3 = ...
[root setObject:item1 forKey:#"Item 1"];
[root setObject:item2 forKey:#"Item 2"];
Also did some research and tried something else with some other input..
NSMutableArray *Rows = [NSMutableArray arrayWithCapacity: 1];
for (int i = 0; i < 4; ++i) {
NSMutableArray *theChildren = [NSMutableArray arrayWithCapacity: 1];
[theChildren addObject: [NSString stringWithFormat: #"tester %d", i]];
NSString *aTitle = [NSString stringWithFormat: #"Item %d", i];
NSDictionary *anItem = [NSDictionary dictionaryWithObjectsAndKeys: aTitle, #"Title", theChildren, #"Children"];
[Rows addObject: anItem];
}
NSDictionary *Root = [NSDictionary withObject: Rows andKey: #"Rows"];
I decided to just test both of these however it does what I want. It gives me a EXC_BAD_ACCESS error.
I was also wondering since I saw you using number in your code snippet, couldn't you also use NSString since that's what the plist uses.. could be totally of here of course
NSDictionary *item1 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:#"Screen J",[NSNumber numberWithInt:3],nil]
forKeys:[NSArray arrayWithObjects:#"Title",#"View",nil]];
and third a question is about my possible approach to my app.
I have an xml parser which saves certain information in different arrays.
I want to use this information for my drilldown UITableviews (infoFirstScreen[] infoSecondScreen[] infoThirdScreen[]).
The information provided has to be connected like the tree I showed you above.
This is the reason I wanted to build the dictionary in code so I can take the info from my arrays and insert it here.
My question do you think my approach is correct, wrong or is there a faster way?
again really appreciate the explanation ;)