hi i want to display string combination on nslog like this format
abc
bca
acb
and so on
but
my program show me it like this format
permutations =
(
(
c,
b,
a
),
(
b,
c,
a
),
(
c,
a,
b
),
(
a,
c,
b
),
(
b,
a,
c
),
(
a,
b,
c
)
)
this is the code i am using
NSArray *array = [NSArray arrayWithObjects:#"a",#"b",#"c",nil];
NSMutableArray *permutations = nil;
int i = 0;
for (i = 0; i < array.count ; i++){
if (!permutations){
permutations = [NSMutableArray array];
for (NSString *character in array){
[permutations addObject:[NSArray arrayWithObject:character]];
}
} else {
//make copy of permutations array and clean og array
NSMutableArray *aCopy = [permutations copy] ;
[permutations removeAllObjects];
for (NSString *character in array){
//loop through the copy
for (NSArray *oldArray in aCopy){
//check if old string contains looping char..
if ([oldArray containsObject:character] == NO){
//update array
NSMutableArray *newArray = [NSMutableArray arrayWithArray:oldArray];
[newArray addObject:character];
//add to permutations
[permutations addObject:newArray];
}
}
}
}
}
NSLog(#"permutations = \n %#",permutations);
}
kindly tell me how i can display it in my require format
Try this way :
NSString *stringPermuted=[NSString new];
for (NSArray *array in permutations) {
for (NSString *string in array) {
stringPermuted=[stringPermuted stringByAppendingFormat:#"%#",string];
}
stringPermuted=[stringPermuted stringByAppendingFormat:#"\n"];
}
NSLog(#"permutations=\n%#",stringPermuted);
Another Way :
NSString *stringPermuted=[NSString new];
for (NSArray *array in permutations) {
stringPermuted=[stringPermuted stringByAppendingFormat:#"%#\n",[array componentsJoinedByString:#""]];
}
NSLog(#"permutations=\n%#",stringPermuted);
Create a simple method for displaying
- (NSString *)formatPermutations:(NSArray *)permutations {
NSString * formattedPermutations = #"";
for (NSArray * permutation in permutations) {
formattedPermutations = [formattedPermutations stringByAppendingFormat:#"%#\n", [self formatPermutation:permutation]];
}
return formattedPermutation;
}
- (NSString *)formatPermutation:(NSArray *)permutation {
NSString * formattedPermutation = #"";
for (NSString * letter in permutation) {
formattedPermutation = [formattedPermutation stringByAppendingString:letter];
}
return formattedPermutation;
}
and use it
NSLog(#"permutations = \n %#",[self formatPermutations:permutations]);
Another option (and maybe preferable option) would be to create your own classes and PermutationArray and Permutation and override their description method.
Such method is the equivalent of a Java toString and it gets called whenever NSLog needs to get a NSString representation out of an object.
With your last line NSLog(#"permutations = \n %#",permutations); you are logging the entire NSMutableArray in the console. Xcode is formatting it like that to make it more readable.
Try logging your results this way:
Updated version:
for (NSArray *permutation in permutations){
NSMutableString *tempString = [[NSMutableString alloc] initWithString:#""];
for(NSString *character in permutation){
[tempString appendString:character]
}
NSLog(#"%#\n",tempString);
}
Your permutations object is an NSArray of NSArrays. When using NSLog to log it, NSLog will invoke the description method of NSArray and this uses linebreaks to split up eacho f the objects in the array.
If you want to change the way it is printed you can either use your own NSArray subclass and overwrite the description method or just write a slightly more complicated log statement like so:
Quick and Dirty
for (NSArray *arrayOfStrings in permutations) {
for (NSString *oneCharacterString in arrayOfStrings) {
printf("%s", [oneCharacterString UTF8String]);
}
printf(" ");
}
Little bit less quick a lot less dirty
// with linebreaks after each permutation
// If you don't want those, move the NSLog out of the for loop construct one big string to log in the format you like
for (NSArray *arrayOfStrings in permutations) {
NSMutableString *permutationString = [NSMutableString string];
for (NSString *oneCharacterString in arrayOfStrings) {
[permutationString appendString:oneCharacterString]
}
NSLog(permutationString);
}
Other comments: If you want to save only onecharacter anyway you could also use an NSNumber object (create it using [NSNumber numberWithChar:]).
Or you could use NSString or NSMutableString instead of the inner arrays.
Related
I found a workaround myself, but still trying to understand the problem.
I created a Autocomplete text field with the use of uitableview which is hidden until textfield is edited. The UI part works fine. It's the searching for the results part that's the problem. I declared a local NSMutableDictionary to store my results because I wanted the results to be sorted by the key's values.
if I call keysSortedByValueUsingSelector on the dictionary directly, it crashes. However if I get the keys by [dict allKeys] first, then call sortedArrayUsingSelector, it works fine:
// This commented out line will crash
// NSArray *sortedKeysArray = [dict keysSortedByValueUsingSelector:#selector(compare:)];
// The next two lines runs fine.
NSArray *keyArray = [dict allKeys];
NSArray *sortedKeysArray = [keyArray sortedArrayUsingSelector:#selector(compare:)];
Here is the complete source code for the search method:
- (void)searchAutocompleteEntriesWithSubstring:(NSString *)substring
{
// Put anything that starts with this substring into the autocompleteUrls array
// The items in this array is what will show up in the table view
[autocomplete_symbol_array removeAllObjects];
rRSIAppDelegate *appDelegate = (rRSIAppDelegate *)([[UIApplication sharedApplication] delegate]);
NSString *input_str = [substring uppercaseString];
NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
int i = 0;
for(SymbolInfo *symbol_info in appDelegate.m_symbol_info_array)
{
i++;
NSString *info_str = [[[symbol_info.m_symbol uppercaseString] stringByAppendingString:#"|"] stringByAppendingString:[symbol_info.m_company_name uppercaseString]];
NSUInteger pos = [info_str rangeOfString:input_str].location;
if (pos != NSNotFound)
{
int tmp = pos * 10000 + i;
NSNumber *map_key = [[NSNumber alloc] initWithInt:tmp];
[dict setObject:symbol_info forKey:map_key];
}
}
// This commented out line will crash
// NSArray *sortedKeysArray = [dict keysSortedByValueUsingSelector:#selector(compare:)];
// The next two lines runs fine.
NSArray *keyArray = [dict allKeys];
NSArray *sortedKeysArray = [keyArray sortedArrayUsingSelector:#selector(compare:)];
for (NSNumber *key in sortedKeysArray)
{
SymbolInfo *symbol_info = [dict objectForKey:key];
[autocomplete_symbol_array addObject:symbol_info];
}
// NSLog(#"everything added: %d", [autocomplete_symbol_array count]);
[autocompleteTableView reloadData];
}
The NSMutableDictionary's method is:
- (void)setObject:(id)anObject forKey:(id < NSCopying >)aKey;
This means that the key should implement the NSCopying protocol.
I'm trying to extract the weather information from here using Xpath on the iPhone. As of now it parses all the data but I'm stuck on how to extract the content and display it in a table.
This is what I have so far:
NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:[ #"http://aviationweather.gov/adds/metars/?station_ids=1234&std_trans=translated&chk_metars=on&hoursStr=most+recent+only&submitmet=Submit"stringByReplacingOccurrencesOfString:#"1234" withString:self.title]]];
TFHpple * doc = [[TFHpple alloc] initWithHTMLData:data];
NSArray * elements = [doc searchWithXPathQuery:#"//table[1]//tr"];
NSLog(#"%#", elements);
TFHppleElement * element = [elements objectAtIndex:0];
[element content]; // Tag's innerHTML
[element tagName]; // "a"
[element attributes]; // NSDictionary of href, class, id, etc.
[element objectForKey:#"href"]; // Easy access to single attribute
If anybody needs to see what its outputting so far, let me know.
Thanks,
Andrew
I had the same issue I got to the point your at and didn't no where to go but I end up implementing this code. Hope it helps there is still little bits need to make it work correctly but do to the nature of the app I have developed this is all I can give you. its not much more its just the actual implementation into your code that you need really.
#import "XPathQuery.h"
NSMutableArray *weatherArray = [[NSMutableArray arrayWithArray:0]retain]; // Initilize the NSMutableArray can also be done with just an NSArray but you will have to change the populateArray method.
NSString *xPathLookupQuery = #"//table[1]//tr"; // Path in xml
nodes = PerformXMLXPathQuery(data, xPathLookupQuery); // Pass the data in that you need to search through
[self populateArray:weatherArray fromNodes:nodes]; // To populate multiple values into array.
session = [[self fetchContent:nodes] retain]; // To populate a single value and returns value.
- (void)populateArray:(NSMutableArray *)array fromNodes:(NSArray *)nodes
{
for (NSDictionary *node in nodes) {
for (id key in node) {
if ([key isEqualToString:#"nodeContent"]) {
[array addObject:[node objectForKey:key]];
}
}
}
}
You only need either the above code or below code unless you want both.
- (NSString *)fetchContent:(NSArray *)nodes
{
NSString *result = #"";
for (NSDictionary *node in nodes) {
for (id key in node) {
if([key isEqualToString:#"nodeContent"]) {
result = [node objectForKey:key];
}
}
}
return result;
}
I am having a bit of trouble navigating around an NSArray.
My array:
Element[0] = "ElementA"
Element[1] = "ElementA"
Element[2] = "ElementA"
Element[3] = "ElementA"
Element[4] = "ElementB"
Element[5] = "ElementC"
Are there any methods in Objective-C that will help me find the "median" element? In this case, the "median" would be "ElementA", or the value that occurs the maximum number of times.
In C# this would be a single call, but I can't find an equivalent in Objective-C.
Many thanks,
Brett
Here's how I'd do it:
NSArray * elements = ...; //your array of elements:
NSCountedSet * counts = [NSCountedSet setWithArray:elements]:
id modeObject = nil;
NSUInteger modeCount = 0;
for (id element in counts) {
if ([counts countForObject:element] > modeCount) {
modeCount = [counts countForObject:element];
modeObject = element;
}
}
NSLog(#"element with highest frequency: %#", modeObject);
An NSCountedSet is an NSMutableSet that also remembers how many times its elements have been added to the array.
Wrote this just for you :)
- (NSString *) findModeString: (NSArray *) array {
NSMutableDictionary *stats = [[NSMutableDictionary alloc] init];
for(NSString *str in array) {
if(![stats objectForKey:str]) {
[stats setObject: [NSNumber numberWithInt:1] forKey:str];
} else {
[stats setObject: [NSNumber numberWithInt:[[stats objectForKey:str] intValue] + 1] forKey:str];
}
}
NSInteger maxOccurrences = 0;
NSString *max;
for(NSString *key in stats) {
if([[stats objectForKey:key] intValue] > maxOccurrences) {
max = key;
maxOccurrences = [[stats objectForKey:key] intValue];
}
}
[stats release];
return max;
}
EDIT: Although my solution works, you should upvote/accept #Dave DeLong's answer, it is much much better.
Couldn't you just use:
[myarray length] /2
I'm trying to include the elements of an array in the NSString that's returned by the -description method in my class. No clue how to do this in Objective-C...in Java there's string concatenation or StringBuilder, what's the equivalent in Obj-C?
TIA..
Just use NSArray's componentsJoinedByString: method with whatever you want between them as the argument.
NSString *elementsSquishedTogether = [myArray componentsJoinedByString:#""];
NSString *connectedByACommaAndSpace = [myArray componentsJoinedByString:#", "];
If you have a C array, you can turn it into an NSArray with NSArray *converted = [NSArray arrayWithObjects:yourCArray count:yourArrayCount].
The title of your thread talks about C arrays, so here's a modification of jsumners' answer that will deal wiith C arrays.
myArray is assumed to be an ivar declared thusly:
int* myArray;
storage for myArray is assumed to be malloc'd at some point and the size of it is in an ivar declared:
int myArraySize;
The code for description goes something like
- (NSString *)description
{
NSMutableString *returnString = [[[NSMutableString alloc] init] autorelease];
for (int i = 0 ; i < myArraySize ; i++)
{
if (i > 0)
{
[returnString appendString: #", "];
}
[returnString appendFormat: #"%d", myArray[i]];
}
return [NSString stringWithFormat: #"[%#]", returnString];
}
There are variations. The above version formats the string with bracket delimiters and commas between elements. Also, it returns an NSString instead of an NSMutableString which is not a big deal, but I feel that if you say you are returning an immutable object, you probably should.
The following could should "build" a string representation of your array. Notice that it is using the -description method of the objects in the array. If you want something different you will have to make the necessary change.
- (NSString *)description: (id) myArr {
NSMutableString *returnString = [[[NSMutableString alloc] init] autorelease];
for (int i = 0, j = [myaArr count]; i < j; i++) {
[returnString appendString: [[myArr objectAtIndex: i] description]];
}
return [NSString stringWithString: returnString];
}
Edit:
As JeremyP said, I answered this using Objective-C arrays. I guess I just forgot the question when I started writing my code. I'm going to leave my answer as an alternative way to do it, though. I've also fixed the return string type from a mutable string to an immutable string (as it should be).
I want to call a method which returns two values
basically lets say my method is like the below (want to return 2 values)
NSString* myfunc
{
NSString *myString = #"MYDATA";
NSString *myString2 = #"MYDATA2";
return myString;
return myString2;
}
So when i call it, i would use??
NSString* Value1 = [self myfunc:mystring];
NSString* Value2 = [self myfunc:mystring2];
I guess im doing something wrong with it, can anyone help me out?
Thanks
You can only return 1 value. That value can be a struct or an object or a simple type. If you return a struct or object it can contain multiple values.
The other way to return multiple values is with out parameters. Pass by reference or pointer in C.
Here is a code snippet showing how you could return a struct containing two NSStrings:
typedef struct {
NSString* str1;
NSString* str2;
} TwoStrings;
TwoStrings myfunc(void) {
TwoStrings result;
result.str1 = #"data";
result.str2 = #"more";
return result;
}
And call it like this:
TwoStrings twoStrs = myfunc();
NSLog(#"str1 = %#, str2 = %#", twoStrs.str1, twoStrs.str2);
You need to be careful with memory management when returning pointers even if they are wrapped inside a struct. In Objective-C the convention is that functions return autoreleased objects (unless the method name starts with create/new/alloc/copy).
You have a few options:
NSArray: Just return an array. Pretty simple.
Pointers: Pass in two pointers, and write to them instead of returning anything. Make sure to check for NULL!
Structure: Create a struct that has two fields, one for each thing you want to return, and return one of that struct.
Object: Same a structure, but create a full NSObject subclass.
NSDictionary: Similar to NSArray, but removes the need to use magic ordering of the values.
As you can only return one value/object, maybe wrap them up in an array:
-(NSArray*) arrayFromMyFunc
{
NSString *myString = #"MYDATA";
NSString *myString2 = #"MYDATA2";
return [NSArray arrayWithObjects:myString,myString2,nil];
}
You can then use it like this:
NSArray *arr = [self arrayFromMyFunc];
NSString *value1 = [arr objectAtIndex:0];
NSString *value2 = [arr objectAtIndex:1];
You could pass results back by reference, but this is easy to get wrong (syntactically, semantically, and from memory management point of view).
Edit One more thing: Make sure that you really need two return values. If they are quite independent, two separate function are often the better choice - better reusabilty and mentainable. Just in case you are making this as a matter of premature optimization. :-)
You can only directly return one value from a function. But there is a way of doing it.
-(void) myfuncWithVal1:(NSString**)val1 andVal2:(NSString**)val2
{
*val1 = #"MYDATA";
*val2 = #"MYDATA2";
}
Then to call it outside the method you'd use:
NSString* a;
NSString* b;
[self myfuncWithVal1:&a andVal2:&b];
void myfunc(NSString **string1, NSString **string2)
{
*string1 = #"MYDATA";
*string2 = #"MYDATA2";
}
...
NSString *value1, *value2;
myfunc(&value1, &value2);
Remember that you need to pass a pointer to a pointer when working with strings and other objects.
Wrap the two strings in an NSArray:
- (NSArray*)myFunc
{
NSString *myString = #"MYDATA";
NSString *myString2 = #"MYDATA2";
return [NSArray arrayWithObjects:myString, myString2, nil];
}
NSArray *theArray = [self myFunc]
NSString *value1 = [theArray objectAtIndex:0];
NSString *value2 = [theArray] objectAtIndex:1];
I see everyone has mentioned an NSArray but I'd go with an NSDictionary so the values don't have to be added in order or even at all. This means it is able to handle a situation where you only want to return the second string.
- (NSDictionary*)myFunction {
NSString *myString1 = #"string1";
NSString *myString2 = #"string2";
return [NSDictionary dictionaryWithObjectsAndKeys: myString1, #"key1", myString2, #"key2", nil];
}
NSDictionary *myDictionary = [self myFunction]
NSString *string1 = [myDictionary objectForKey:#"key1"];
NSString *string2 = [myDictionary objectForKey:#"key2"];