Okay I am learning about arrays and how to work with them like I used to...... (Used to do alot of scripting but now am trying to learn to develop ipad and iphone app's
But my issue is I have it where it pulls a bunch of data from yahoo finance with a for loop..
But now my issue is how can I work with just one peice of the array data that has been pulled
here is my example
-(IBAction) clicked:(id)sender {
NSString * StockOneYahooFinance = [NSString stringWithFormat:#"http://finance.yahoo.com/q/hp?s=S+Historical+Prices"];
NSString * PulledStockOne = [NSString stringWithContentsOfURL:[NSURL URLWithString:StockOneYahooFinance] encoding:1 error:nil];
for (i=1;i<=10;i++){
NSString *StartPulling = [[PulledStockOne componentsSeparatedByString:#"nowrap align="] objectAtIndex:i];
NSString *StartOpen = [[StartPulling componentsSeparatedByString:#">"] objectAtIndex:3];
NSString *Open = [[StartOpen componentsSeparatedByString:#"<"] objectAtIndex:0];
NSString *StartClose = [[StartPulling componentsSeparatedByString:#">"] objectAtIndex:9];
NSString *Close = [[StartClose componentsSeparatedByString:#"<"] objectAtIndex:0];
NSMutableArray *StockOpens = [[NSMutableArray alloc] initWithCapacity:6];
[StockOpens addObject:Open];
sixtyday.text = [OpenValues objectAtIndex:10];
nintyday.text = [CloseValues objectAtIndex:10];
if ([OpenValues objectAtIndex:10]=[OpenValues objectAtIndex:11] {
sevenday.text = #"Plus One";
}
}
}
But now I want to do something like
year.text=StockOpens[5];
How can I do this.
Starting in Xcode 4.4 (LLVM 4.0), literals can be used for C-style subscripting in Objective-C.
year.text = StockOpens[5];
LLVM has documented the use of literal here: Objective-C Literals
Note: Because Clang will translate the literal usage, in this case to objectAtIndexedSubscript:, the OS X v10.8 (or iOS 6) Foundation framework is required.
StockOpens is an array object so you need to call a method to get the object at an index. On NSMutableArray its [StockOpens ObjectAtIndex:5]
year.text = [[StockOpens objectAtIndex:5]StringValue];
To do StockOpens[5] you need to use a C-array.
This depends on what kind/class of objects you fill StockOpens with, if it's simply NSStrings, you can do
year.text = [StockOpens objectAtIndex:5];
If it's some other object that is not a string, you can maybe call its description:
year.text = [[StockOpens objectAtIndex:5] description];
P. s.: there's documentation on developer.apple.com, please read it! This question is so simple (and fundamental) that it must not be asked on SO.
Related
I'm using this code to load content to NSArray and it seem to work fine however Instrument to detect leaks point that there is a problem that I can't put my finger on:
- (void) loadPlan: (NSString *) fName
{
short j1;
fName= [NSString stringWithFormat:#"/%#", fName];
[self NewCase];
NSArray *arrayPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *docDirectory = [arrayPaths objectAtIndex:0];
NSString *filePath = [docDirectory stringByAppendingString:fName];
BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:filePath];
if (!fileExists) return;
NSString *fileContents = [NSString stringWithContentsOfFile:filePath
encoding:NSUTF8StringEncoding error:nil];
NSArray *chunks = [fileContents componentsSeparatedByString: #"#"];
for (i = 0; i <= 100; i++)
{
InputV[i] = [[chunks objectAtIndex: i+5] doubleValue];
}
...
for (j1 = 0; j1 <= 10; j1++)
{
GroupMode[j1] = [[chunks objectAtIndex: 206+j1] retain];
}
...
}
and on a init method someplace i have:
for (j1 = 0; j1 <= 10; j1++)
{
GroupMode[j1] = [[NSString alloc] initWithFormat:#""];
}
Instrument points to the NSAraay *chunks line code but i'm not sure what's the issue. Do i need to release it at some point ?
I appreciate any help.
In the comments you mention being able to call release. Therefore you are not using ARC and since I noticed you tagged with iphone you are not using GC. This leaves manual memory management.
The problem seems to be that either the chunks array or some chunks themseves are overretained (or underreleased). You are not showing all the code, so it's hard to say.
Make sure you do not retain either of them somewhere else in the code you did not show. Maybe show us the rest of the loadPlan method implementation.
edit: Now that you added more code, I can also expand this answer.
Answer this question: where is the retain call to the chunks matched with a release?
Also what is the declaration of GroupMode? It seems to be just an array of pointers. If so you probably need to release the old value before setting the new one.
Let me try another answer based on what you posted.
I'm assuming GroupMode is an instance variable of some class and is declared like this:
NSString* GroupMode[11];
The second loop in loadPlan should be:
for (j1 = 0; j1 <= 10; j1++)
{
NSString* aChunk = [chunks objectAtIndex: 206+j1];
if ( GroupMode[j1] != aChunk ) {
[GroupMode[j1] release];
GroupMode[j1] = [aChunk retain];
}
}
You should do something similar every time you change an element of GroupMode and you should make sure you release all GroupMode held objects in the dealloc method of that class.
I however suggest you do not use plain arrays and instead switch to using NSArray and/or NSMutableArray.
Take a look at this answer:
"componentsSeparatedByString" Memory leak
The problem is probably that something using the results is over-retaining the stuff from chunks. Instruments is pointing at this line because it's where the memory was first allocated, but it may not be the source of your problem.
After trying to print retainCount of object I get 2147483647. Why do I get such a result? It should be 1, shouldn't?
NSString *myStr = [NSString new];
NSUInteger retCount = [myStr retainCount];
NSLog(#"refCount = %u", retCount);
2011-09-08 17:59:18.759 Test[51972:207] refCount = 2147483647
I use XCode Version 4.1. Tried compilers GCC 4.2 and LLVM GCC 4.2 - the same result.
Garbage Collection option was set to unsupported.
NSString is somewhat special when it comes to memory management. String literals (something like #"foo") are effectively singletons, every string with the same content is the same object because it can't be modified anyway. As [NSString new] always creates an empty string that cannot be modified, you'll always get the same instance which cannot be released (thus the high retainCount).
Try this snippet:
NSString *string1 = [NSString new];
NSString *string2 = [NSString new];
NSLog(#"Memory address of string1: %p", string1);
NSLog(#"Memory address of string2: %p", string2);
You'll see that both strings have the same memory address and are therefore the same object.
This doesn't directly answer your question, but retainCount is not really all that useful and should not be used for testing. See this SO post for details.
When to use -retainCount?
While NSString's are an odd case (there are others in the framework) you might also run across this in other clases - it's one of the ways of creating a singleton object.
A singleton only exists once in the app and it's pretty important that it never gets released! Therefore, it will overwrite some methods of NSObject including (but not limited to):
- (id)release {
// Ignore the release!
return self;
}
- (NSUInteger)retainCount {
// We are never going to be released
return UINT_MAX;
}
This object can never be released and tells the framework that it's a singleton by having a ludicrously high retain count.
Checkout this link for more information about singleton objects.
I've seen this a couple of times regarding NSStrings, the retainCount returns the maximum count instead of the actual one when you try to look at retainCounts of strings in this manner.
Try this;
NSString *myStr = [[NSString alloc] init];
NSUInteger retCount = [myStr retainCount];
NSLog(#"refCount = %u", retCount);
Edit: Restored NSUInteger
//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];
I’m making a languages application, and I have a long list of vocabulary relating to that language (German, in case anyone was interested). I have the functionality in my app to switch between sorting the tableview by German words, or by english words.
When I use the following:
NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:type];
NSString *string = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];
NSArray *array = [[string componentsSeparatedByString:#"\n"] sortedArrayUsingSelector:#selector(compare:)];
it works absolutely perfectly - by which I mean, exactly as expected. What I would like to improve on this however, is that there are certain words, such as verbs or nouns, which are always preceded by prefixes, like “to”, as in “to do something”, or “the” in front of nouns. So what I would like to do is somehow exclude these from my sort, because otherwise I end up with all the verbs being sorted alphabetically under the “t” section in my array, which is not very user friendly.
I’ve looked through the Apple documentation about NSString and NSArray, as this is where the compare function is (unless I’m very much mistaken), and I haven’t found any way that makes sense to me. This is the first time I have done any data handling like this so I may be missing something simple, and so I would really appreciate some help.
Thanks very much
Michaeljvdw
You're on the right track. What you want to use instead of the (built-in) compare method is to write your own method, which can eliminate the "to" or "the" bits if they exist, and then use the existing compare method.
Your call would look something like this:
NSArray *array = [[string componentsSeparatedByString:#"\n"] sortedArrayUsingSelector:#selector(myCompare:)];
Using a custom category you give to NSString with the following methods:
// This method can be exposed in a header
- (NSComparisonResult)myCompare:(NSString*)aString
{
NSString* selfTrimmed = [self removeArticles];
NSString* aStringTrimmed = [s2 removeArticles];
return [self compare:aString];
}
// This method can be kept private in the .m implementation
- (NSString*)removeArticles
{
NSRange range = NSMakeRange(NSNotFound, 0);
if ([self hasPrefix:#"to "])
{
range = [self rangeOfString:#"to "];
}
else if ([self hasPrefix:#"the "])
{
range = [self rangeOfString:#"the "];
}
if (range.location != NSNotFound)
{
return [self substringFromIndex:range.length];
}
else
{
return self;
}
}
You might have some luck with localizedCompare: or localizedStandardCompare:, but I don't think that either of these will strip out articles and prepositions like you want. Instead, you will probably have to define a category on NSString that provides the specific style of sorting you're looking for:
#interface NSString (MySortAdditions)
- (NSComparisonResult)compareWithoutArticles:(NSString *)other;
#end
#implementation NSString (MySortAdditions)
- (NSComparisonResult)compareWithoutArticles:(NSString *)other {
NSMutableString *mutableSelf = [NSMutableString stringWithString:self];
[mutableSelf
replaceOccurrencesOfString:#"das"
withString:#""
options:NSCaseInsensitiveSearch
range:NSMakeRange(0, [mutableSelf length])
];
...
// delete articles from 'other' too
NSCharacterSet *trimSet = [NSCharacterSet whitespaceAndNewlineCharacterSet];
NSString *trimmedSelf = [mutableSelf stringByTrimmingCharactersInSet:trimSet];
NSString *trimmedOther = ...;
return [trimmedSelf localizedCaseInsensitiveCompare:trimmedOther];
}
#end
You can then use #selector(compareWithoutArticles:) as your sort selector for NSArray.
First, don't use compare:. Use localizedCompare: instead. This is important, because whether á appears just after a or after z as a separate letter depends on the language. localizedCompare: takes care of that.
--edit
As Justin says, localizedStandardCompare: is the selector to be used! I didn't know that method. As written in the documentation, localizedStandardCompare: does more than localizedCompare:, although the document doesn't say exactly what it does.
--end of edit
If you want more, you need to implement that yourself. You can use category for that purpose. First declare it
#interface NSString (MichaelsSuperCompareCategory)
-(NSComparisonResult)michaelsSuperCompare:(NSString*)string;
#end
and then implement it
#interface NSString (MichaelsSuperCompareCategory)
-(NSComparisonResult)michaelsSuperCompare:(NSString*)string{
...
}
#end
This way you can add methods to an existing class. Then you can use
NSArray *array = [[string componentsSeparatedByString:#"\n"]
sortedArrayUsingSelector:#selector(michaelsSuperCompare:)];
It is important to prefix the method name with something distinctive, not to accidentally crash with internal methods used by Apple.
As for the functionality, you need to implement that yourself, as far as I know. You can get the current locale with [NSLocale currentLocale]. You can implement a nicer behavior for the languages you know, and then default to localizedCompare: for unknown languages.
I would somehow do -replaceOccurancesOfStrings on all the data eg "To" -> "" - and then reload the data. (or this can in a text editor)
Another thing to think about is having eg 'to walk' changed to 'walk (to)' which can be done ahead of time (and will also create less confusion for the user as they are scrolling alphabetically).
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