I have NSTableView with two columns, and i wanna fill them entries from SQLite database.
this method is make query for table
-(void)getPersons
{
NSString *file = [[NSBundle mainBundle] pathForResource:#"persons" ofType:#"db"];
sqlite3 *database = NULL;
if (sqlite3_open([file UTF8String], &database)==SQLITE_OK)
{
NSLog(#"i open database");
sqlite3_exec(database, "select name,age from persons", MyCallback, persons, NULL);
}
sqlite3_close(database);
}
the problem appers in MyCallback method:
static int MyCallback(void *context, int count, char **values, char **columns)
{
NSMutableArray *persons = (NSMutableArray *)context;
for (int i=0; i < count; i++) {
NSString *columnname = [NSString stringWithUTF8String:columns[i]];
const char *nameCString = values[i];
if ([columnname isEqualTo:#"name"]) {
[persons addObject:[NSString stringWithUTF8String:nameCString]];
}
else {
[ages addObject:[NSString stringWithUTF8String:nameCString]];
}
}
return SQLITE_OK;
}
how can i write "age" entries into NSMutableArray *ages, if i can assign *context just for one NSMutableArray? (in this code, this is NSMutableArray *person)
Surely i should create a separate method for get age entries?
thanks.
In many simple cases like the one in your question it is convinient use most natural representation of tables in objective-c: array of dictionaries. Table is indexed collection of records - so it is an array, and each record is collection of key-value pairs - so it is a dictionary. And you need not change you code when you change column names or even number of colums.
...
NSMutableArray *allRecords= (NSMutableArray *)context;
NSString *columnName;
NSString *columnValue;
NSMutableDictionary * record = [NSMutableDictionary dictionary];
for (int i=0; i < count; i++) {
columnName = [NSString stringWithUTF8String:columns[i]];
if (values[i]){
columnValue = [NSString stringWithUTF8String:values[i]];
}
else{
columnValue = #"";
}
[record setObject:columnValue forKey:columnName];
}
[allRecords addObject:record];
...
Related
I have 2 arrays that receive information from a database. One, called json, contains posts with user id's and the other, called userJson, contains all the users with their id's. If the the user id from json equals a user id from userJson, I would like to populate a 3rd array with that users username. I am using the following code:
NSDictionary *info = [json objectAtIndex:indexPath.row];
NSDictionary *userInfo = [userArray objectAtIndex:0];
for (int i=0; i<[json count]; i++) {
if ([[userInfo objectForKey:#"user_id"] isEqualToString:[info objectForKey:#"user_id"]]) {
[usernameArray addObject:[userInfo objectForKey:#"username"]];
}
}
NSLog(#"%#", usernameArray);
usernameArray is the 3rd array that should contain the usernames. When I print it, it prints out null various times.
You need to first add this:
usernameArray = [[NSMutableArray alloc]init];
Then change your loop to the following:
NSDictionary *info = [json objectAtIndex:indexPath.row];
NSDictionary *userInfo;
for (int i=0; i<[userArray count]; i++) {
userInfo = [userArray objectAtIndex:i];
if ([[userInfo objectForKey:#"user_id"] isEqualToString:[info objectForKey:#"user_id"]]) {
[usernameArray addObject:[userInfo objectForKey:#"username"]];
}
}
I have filled a NSMutableArray with integer and string values from my database.
The problem is that many values were inserted more than once.
Using the following code I remove duplicate objects
for (id object in originalArray) {
if (![singleArray containsObject:object]) {
[singleArray addObject:object];
}
}
Bus this works only if the objects are exactly the same between them.
Is there a way to remove duplicates based on the integer value?
EDIT (from an OP's comment on a deleted answer)
I have some objects containing int and NSString. For example #"John 13", #"Mary 25", #"Luke 25", #"Joan 13". The NSMutableArray will contain all four names and duplicates of 13, 25. I want to remove the duplicates leaving 13 and 25 only once in the array. I do not care which names will be removed. Care only for the integer values to use them later.
If your elements are all NSNumber objects:
for (int i=0;i<array.count;i++) {
for (int j=i+1;j<array.count;j++) {
if ([array[i] isEqualToNumber:array[j]]) {
[array removeObjectAtIndex:j--];
}
}
}
Or if all objects are either integer NSNumbers or NSStrings containing integer values:
for (int i=0;i<array.count;i++) {
for (int j=i+1;j<array.count;j++) {
if ([array[i] intValue] == [array[j] intValue]) {
[array removeObjectAtIndex:j--];
}
}
}
Try this:
// singleArray is initially empty
for (id object in originalArray)
{
BOOL contains= YES;
for( id single in singleArray)
{
if( [single integerValue]==[object integerValue] )
{
contains= NO;
break;
}
}
if(contains)
{
[singleArray addObject: object];
}
}
no test, tell me if it does not work. assuming objects in the array are string and format is "WORD NUMBER"
Boolean myEqual(const void *value1, const void *value2) {
NSString *str1 = (__bridge NSString *)(value1);
NSString *str2 = (__bridge NSString *)(value2);
NSArray *arr1 = [str1 componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
NSArray *arr2 = [str2 componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
return [[arr1 lastObject] isEqual:[arr2 lastObject]];
}
CFHashCode myHash(const void *value) {
NSString *str1 = (__bridge NSString *)(value);
NSArray *arr1 = [str1 componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
return [[arr1 lastObject] hash];
}
NSMutableArray *array = // your array;
CFSetCallBacks callBacks = kCFTypeSetCallBacks;
callBacks.equal = myEqual;
callBacks.hash = myHash;
CFMutableSetRef set = CFSetCreateMutable(NULL, [array count], &callBacks);
for (id obj in [array copy]) { // copy so can modify the original array
if (CFSetContainsValue(set, (__bridge const void *)(obj))) {
[array removeObject:obj];
} else {
CFSetAddValue(set, (__bridge const void *)(obj));
}
}
I'm trying to re-arrange words into alphabetical order. For example, tomato would become amoott, or stack would become ackst.
I've found some methods to do this in C with char arrays, but I'm having issues getting that to work within the confines of the NSString object.
Is there an easier way to do it within the NSString object itself?
You could store each of the string's characters into an NSArray of NSNumber objects and then sort that. Seems a bit expensive, so I would perhaps just use qsort() instead.
Here it's provided as an Objective-C category (untested):
NSString+SortExtension.h:
#import <Foundation/Foundation.h>
#interface NSString (SortExtension)
- (NSString *)sorted;
#end
NSString+SortExtension.m:
#import "NSString+SortExtension.h"
#implementation NSString (SortExtension)
- (NSString *)sorted
{
// init
NSUInteger length = [self length];
unichar *chars = (unichar *)malloc(sizeof(unichar) * length);
// extract
[self getCharacters:chars range:NSMakeRange(0, length)];
// sort (for western alphabets only)
qsort_b(chars, length, sizeof(unichar), ^(const void *l, const void *r) {
unichar left = *(unichar *)l;
unichar right = *(unichar *)r;
return (int)(left - right);
});
// recreate
NSString *sorted = [NSString stringWithCharacters:chars length:length];
// clean-up
free(chars);
return sorted;
}
#end
I think separate the string to an array of string(each string in the array contains only one char from the original string). Then sort the array will be OK. This is not efficient but is enough when the string is not very long. I've tested the code.
NSString *str = #"stack";
NSMutableArray *charArray = [NSMutableArray arrayWithCapacity:str.length];
for (int i=0; i<str.length; ++i) {
NSString *charStr = [str substringWithRange:NSMakeRange(i, 1)];
[charArray addObject:charStr];
}
NSString *sortedStr = [[charArray sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)] componentsJoinedByString:#""];
// --------- Function To Make an Array from String
NSArray *makeArrayFromString(NSString *my_string) {
NSMutableArray *array = [[NSMutableArray alloc] init];
for (int i = 0; i < my_string.length; i ++) {
[array addObject:[NSString stringWithFormat:#"%c", [my_string characterAtIndex:i]]];
}
return array;
}
// --------- Function To Sort Array
NSArray *sortArrayAlphabetically(NSArray *my_array) {
my_array= [my_array sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)];
return my_array;
}
// --------- Function Combine Array To Single String
NSString *combineArrayIntoString(NSArray *my_array) {
NSString * combinedString = [[my_array valueForKey:#"description"] componentsJoinedByString:#""];
return combinedString;
}
// Now you can call the functions as in below where string_to_arrange is your string
NSArray *blowUpArray;
blowUpArray = makeArrayFromString(string_to_arrange);
blowUpArray = sortArrayAlphabetically(blowUpArray);
NSString *arrayToString= combineArrayIntoString(blowUpArray);
NSLog(#"arranged string = %#",arrayToString);
Just another example using NSMutableString and sortUsingComparator:
NSMutableString *mutableString = [[NSMutableString alloc] initWithString:#"tomat"];
[mutableString appendString:#"o"];
NSLog(#"Orignal string: %#", mutableString);
NSMutableArray *charArray = [NSMutableArray array];
for (int i = 0; i < mutableString.length; ++i) {
[charArray addObject:[NSNumber numberWithChar:[mutableString characterAtIndex:i]]];
}
[charArray sortUsingComparator:^NSComparisonResult(id _Nonnull obj1, id _Nonnull obj2) {
if ([obj1 charValue] < [obj2 charValue]) return NSOrderedAscending;
return NSOrderedDescending;
}];
[mutableString setString:#""];
for (int i = 0; i < charArray.count; ++i) {
[mutableString appendFormat:#"%c", [charArray[i] charValue]];
}
NSLog(#"Sorted string: %#", mutableString);
Output:
Orignal string: tomato
Sorted string: amoott
I have a NSArray made out of numbers 1..50, which represents a table with columns & rows.
I need to reverse only the order of the columns, while keeping the order of the rows.
So for example:
0,1,2,3,4,5,6
7,8,9,9,10,11,12
has to be
6,5,4,3,2,1,0
12,11,10,9,8,7
Right now, i use a huge IF statement for that:
for (dd *d in dates[i]) {
if (tileNum==0) {
reversedTileNum = 6;
} else if (tileNum==1) {
reversedTileNum = 5;
}else if (tileNum==2) {
reversedTileNum = 4;
}else if (tileNum==3) {
reversedTileNum = 3;
}else if (tileNum==4) {
reversedTileNum = 2;
}else if (tileNum==5) {
reversedTileNum = 1;
} else if (tileNum==6) {
reversedTileNum = 0;
}
....
....
}
Here's a solution that should be easy to drop into any project. It involves two categories: one on NSMutableArray that provides a method to swap objects at two indices, and one on NSArray that provides the -arrayByReversingGroups: method. The idea is to swap the elements in pairs within a group, reversing the group. If number of elements in the array isn't an even multiple of groupSize, the extras at the end are left untouched.
The code presented here is a complete program, so you can see an example of using -arrayByReversingGroups: in the main() function.
#import <Foundation/Foundation.h>
#interface NSArray(Reversible)
-(NSArray*)arrayByReversingGroups:(int)groupSize;
#end
#interface NSMutableArray(Swappable)
-(void)swapObjectAtIndex:(int)first withObjectAtIndex:(int)second;
#end
#implementation NSArray(Reversible)
-(NSArray*)arrayByReversingGroups:(int)groupSize
{
NSMutableArray *newArray = [self mutableCopy];
// Iterate over the array in chunks of groupSize elements. i will be first index in
// the current chunk.
for (int i = 0; (i + groupSize) < [newArray count]; i += groupSize) {
// Iterate over the items in the current chunk, swapping the bth and
// (groupsize-b-1)th elements until they meet at groupsize/2.
for (int b = 0; b <= (groupSize / 2); b++) {
int first = i + b;
int second = i + groupSize - b - 1;
[newArray swapObjectAtIndex:first withObjectAtIndex:second];
}
}
return [newArray copy];
}
#end
#implementation NSMutableArray(Swappable)
-(void)swapObjectAtIndex:(int)first withObjectAtIndex:(int)second
{
id temp = [[self objectAtIndex:second] retain];
[self replaceObjectAtIndex:second withObject:[self objectAtIndex:first]];
[self replaceObjectAtIndex:first withObject:temp];
[temp release];
}
#end
int main (int argc, const char * argv[])
{
#autoreleasepool {
NSArray *array = [NSArray arrayWithObjects:
#"1", #"2", #"3", #"4", #"5", #"6", #"7", #"8", #"9", #"10", #"11", #"12", nil];
NSLog(#"Original: %#", array);
NSLog(#"Reversed: %#", [array arrayByReversingGroups:5]);
}
return 0;
}
I can give you the logic.. you will have to write the code...
First create a function where you pass in an array(here you will send in a row.) then in this function create a new tempeorary array and store all the values for that row in this column then overwrite the original array in reverse order from this new array and return this to the full matrix and store it in there ... hope it helps.
I've created a custom sorting by creating a new category for the NSString class. Below is my code.
#implementation NSString (Support)
- (NSComparisonResult)sortByPoint:(NSString *)otherString {
int first = [self calculateWordValue:self];
int second = [self calculateWordValue:otherString];
if (first > second) {
return NSOrderedAscending;
}
else if (first < second) {
return NSOrderedDescending;
}
return NSOrderedSame;
}
- (int)calculateWordValue:(NSString *)word {
int totalValue = 0;
NSString *pointPath = [[NSBundle mainBundle] pathForResource:#"pointvalues"ofType:#"plist"];
NSDictionary *pointDictionary = [[NSDictionary alloc] initWithContentsOfFile:pointPath];
for (int index = 0; index < [word length]; index++) {
char currentChar = [word characterAtIndex:index];
NSString *individual = [[NSString alloc] initWithFormat:#"%c",currentChar];
individual = [individual uppercaseString];
NSArray *numbersForKey = [pointDictionary objectForKey:individual];
NSNumber *num = [numbersForKey objectAtIndex:0];
totalValue += [num intValue];
// cleanup
individual = nil;
numbersForKey = nil;
num = nil;
}
return totalValue;
}
#end
My question is whether I create a point dictionary to determine the point value associated with each character in the alphabet based on a plist. Then in my view controller, I call
NSArray *sorted = [words sortedArrayUsingSelector:#selector(sortByPoint:)];
to sort my table of words by their point values. However, creating a new dictionary each time the -sortByPoint: method is called is extremely inefficient. Is there a way to create the pointDictionary beforehand and use it for each subsequent call in the -calculateWordValue:?
This is a job for the static keyword. If you do this:
static NSDictionary *pointDictionary = nil
if (pointDictionary==nil) {
NSString *pointPath = [[NSBundle mainBundle] pathForResource:#"pointvalues" ofType:#"plist"];
pointDictionary = [[NSDictionary alloc] initWithContentsOfFile:pointPath];
}
pointDictionary will be persistent for the lifetime of your app.
One other optimization is to build a cache of scores by using this against each of your words:
[dict setObject:[NSNumber numberWithInt:[word calculateWordValue:word]] forKey:word];
Then use the keysSortedByValueUsingSelector: method to extract your list of words (note the selector chould be compare:, since the objects being compared are the NSNumbers).
Finally, the word argument on your method is redundant. Use self instead:
-(int)calculateWordValue {
...
for (int index = 0; index < [self length]; index++)
{
char currentChar = [self characterAtIndex:index];
...
}
...
}
Change your sortByPoint:(NSString *) otherString method to take the dictionary as a parameter, and pass it your pre-created dictionary.
sortByPoint:(NSString *)otherString withDictionary:(NSDictionary *)pointDictionary
EDIT: Won't work because of usage in sortedArrayWithSelector. Apologies. Instead, you may be better off creating a wrapper class for your point dictionary as a singleton which you then obtain a reference to each time your sort function runs.
In calculateWordValue:
NSDictionary *pointDictionary = [[DictWrapper sharedInstance] dictionary];
DictWrapper has an NSDictionary as a property, and a class method sharedInstance (to return the singleton. You have to set that dictionary and pre-initialize it before you do you first sorting.