I'm new to objective c. I am getting my data from an NSArray and want to return value according to some condition. My code is:
NSArray *myData;
NSNumber *day = 5;
myData = [NSArray arrayWithObjects: #"5", nil];
for (int i = 0; i < [myData count]; i++) {
if(day == myData[0]){
NSLog(#"date in valueForDay %# ", da );
return 3;
}
}
Above code doesn't execute my statements (NSLog and return one).
But if i statically compare day with any number it got executed. Like:
NSArray *myData;
NSNumber *day = 5;
myData = [NSArray arrayWithObjects: #"5", nil];
for (int i = 0; i < [myData count]; i++) {
if(day == 5){
NSLog(#"date in valueForDay %# ", da );
return 3;
}
}
can anyone please tell me where i'm doing wrong?
You have created array with string value not with number value. That's why object from your array is "5" which is not equal to integer 5. Make your array as number array.
myData = [NSArray arrayWithObjects: #5, nil];
Also instead of for loop you can simply use indexOfObject to check array having object or not.
NSInteger index = [myData indexOfObject: day];
if(index != NSNotFound) {
return 3;
}
You stored NSString in NSArray. And comparing with NSNumber. You have to add one line above if condition and change your condition.
NSString *myString = [day stringValue];
if([myString isEqualToString:myData[0]])
Related
I have one array with data A=[a,b,c] and another with data B=[d,e,f]. I need to perform this type of operation a.d+ b.e+c.f (Note=Here (.) denotes multplication)and get the result. How can i do that using Objective-C?
Thanks in advance.
Define the function that does the multiplication and addition like this:
- (double)multiply:(NSArray <NSNumber *> *)vector1 withVector:(NSArray <NSNumber *> *)vector2 {
NSAssert(vector1.count == vector2.count, #"Both arrays should contain the same number of elements");
__block double result = 0;
[vector1 enumerateObjectsUsingBlock:^(NSNumber * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
double first = obj.doubleValue;
double second = vector2[idx].doubleValue;
result += first * second;
}];
return result;
}
This uses a block enumeration method on NSArray which gives me in index and a value, which I can use to get the value at the same index in the second array. Note also that I am using a typed array, so I don't have to cast the values to NSNumbers when using them.
Now you can just use the function:
NSArray *a = #[#1, #2, #3];
NSArray *b = #[#4, #5, #6];
NSArray *c = #[#1, #1, #1];
double res1 = [self multiply:a withVector:b]; // => 32.000000
double res2 = [self multiply:b withVector:c]; // => 15.000000
double res3 = [self multiply:c withVector:a]; // => 6.000000
NSNumber *myNum1 = [NSNumber numberWithInt:1];
NSNumber *myNum2 = [NSNumber numberWithInt:2];
NSNumber *myNum3 = [NSNumber numberWithInt:3];
NSArray *a = [NSArray arrayWithObjects: myNum1, myNum2, myNum3, nil];
NSArray *b = [NSArray arrayWithObjects: myNum1, myNum2, myNum3, nil];
int sum=0;
for (int i=0; i<[a count]; i++) {
NSLog(#"%#", (NSNumber*)[a objectAtIndex:i]);
sum =sum +[(NSNumber*)[a objectAtIndex:i] intValue]*[(NSNumber*)[b objectAtIndex:i] intValue];
}
NSLog(#"Sum is %d", sum);
Hope this helps
I have an array containing twenty items. I want to search through the array, comparing one item to the next one in the array, and then print the larger item. I have already sorted the array. I just want to compare the two items, check what the remainder is between the two values, and if it's greater than say, four, print the larger item.
NSArray* arr = [NSArray arrayWithObjects:
[NSNumber numberWithInt:1],
[NSNumber numberWithInt:6],
[NSNumber numberWithInt:7],
[NSNumber numberWithInt:11],
nil
];
int len = [arr count];
for (int i=0; i < len-1; ++i) {
int num1 = [[arr objectAtIndex:i] intValue];
int num2 = [[arr objectAtIndex:i+1] intValue];
if ( num2-num1 > 4 ) {
NSLog(#"%d", num2);
}
}
--output:--
6
NSEnumerator *itemEnumerator = [theArray objectEnumerator];
YourClass *lastObject = [itemEnumerator nextObject];
YourClass *compareObject;
while( (compareObject = [itemEnumerator nextObject]) != nil)
{
if( /* place your condition here */ )
{
NSLog( … );
}
lastObject = compareObject;
}
Typped in Safari
I'm new to Objective-C and I'm trying to create a simple dictionary style app for personal use. Right now I'm attempting to make a loop that prints randomly selected NSArrays that have been added to an NSDictionary. I'd like to print each array only once. Here is the code I'm working with:
NSArray *catList = [NSArray arrayWithObjects:#"Lion", #"Snow Leopard", #"Cheetah", nil];
NSArray *dogList = [NSArray arrayWithObjects:#"Dachshund", #"Pitt Bull", #"Pug", nil];
...
NSMutableDictionary *wordDictionary = [[NSMutableDictionary alloc] init];
[wordDictionary setObject: catList forKey:#"Cats"];
[wordDictionary setObject: dogList forKey:#"Dogs"];
...
NSInteger keyCount = [[wordDictionary allKeys] count];
NSInteger randomKeyIndex = arc4random() % keyCount;
int i = keyCount;
for (i=i; i>0; i--) {
NSString *randomKey = [[wordDictionary allKeys] objectAtIndex:randomKeyIndex];
NSMutableArray *randomlySelectedArray = [wordDictionary objectForKey:randomKey];
NSLog(#"%#", randomlySelectedArray);
}
This code prints the same array "i" times. Any pointers on how to exclude previously printed arrays from being printed again?
I'm wondering if removeObjectForKey: could be of any use.
You just need to re-calculate the random key index every time you go through the loop, and then, as you suggest, use removeObjectForKey:.
Something like this:
NSArray *catList = [NSArray arrayWithObjects:#"Lion", #"Snow Leopard", #"Cheetah", nil];
NSArray *dogList = [NSArray arrayWithObjects:#"Dachshund", #"Pitt Bull", #"Pug", nil];
//...
NSMutableDictionary *wordDictionary = [[NSMutableDictionary alloc] init];
[wordDictionary setObject: catList forKey:#"Cats"];
[wordDictionary setObject: dogList forKey:#"Dogs"];
//...
while ([wordDictionary count] > 0) {
NSInteger keyCount = [wordDictionary count];
NSInteger randomKeyIndex = arc4random() % keyCount;
NSString *randomKey = [[wordDictionary allKeys] objectAtIndex:randomKeyIndex];
NSMutableArray *randomlySelectedArray = [wordDictionary objectForKey:randomKey];
NSLog(#"%#", randomlySelectedArray);
[wordDictionary removeObjectForKey: randomKey];
}
In your code, you generate a random randomKeyIndex, then use it without changing its value i times in the loop. So you get i times the same array.
NSInteger randomKeyIndex = arc4random() % keyCount;
// ...
for (i=i; i>0; i--) {
NSString *randomKey = [[wordDictionary allKeys] objectAtIndex:randomKeyIndex];
// ...
}
As you say removeObjectForKey is an option for you, you can change your code into something like this:
NSInteger keyCount = [[wordDictionary allKeys] count];
for (i=keyCount; i>0; i--) {
NSInteger randomKeyIndex = arc4random() % keyCount;
NSString *randomKey = [[wordDictionary allKeys] objectAtIndex:randomKeyIndex];
NSMutableArray *randomlySelectedArray = [wordDictionary objectForKey:randomKey];
[wordDictionary removeObjectForKey:randomKey];
keyCount--;
NSLog(#"%#", randomlySelectedArray);
}
How can I save the string that match from one NSArray with one index difference in NSMutableArray?
For example, there are three "apple", four "pineapple", six "banana", two "cocoa" and the rest of words dont have duplicate(s) in the nsarray, i would like to know if the nsarray has at least two same words. If yes, I would like to save "apple", "pineapple, "banana" and "cocoa" once in nsmutablearray. If there are other alike words, I would like to add them to namutablearray too.
My code (which still doesn't work properly);
NSArray *noWords = [[NSArray alloc] initWithArray:
[[NSString stringWithContentsOfFile:[[NSBundle mainBundle]
pathForResource:#"words" ofType:#"txt"]
encoding:NSUTF8StringEncoding error:NULL]
componentsSeparatedByString:#"\n"]];
NSUInteger scount = [noWords count];
int ii = 0;
NSString *stringline;
for (ii; ii < scount; ii++)
{
stringline = [noWords objectAtIndex:ii];
NSLog(#"stringline : %# ", stringline);
}
int i = 1;
NSString *line;
for (i ; i < 10; i++)
{
line = [noWords objectAtIndex:i];
NSLog (#"line : %# ", line);
NSMutableArray *douwords = [NSMutableArray array];
if ([stringline isEqualToString:line])
{
NSString *newword;
for (newword in douwords)
{
[douwords addObject:newword];
NSLog (#"detected! %# ", douwords);
}
}
}
Here's a solution using two sets:
- (NSArray *)getDuplicates:(NSArray *)words
{
NSMutableSet *dups = [NSMutableSet set],
*seen = [NSMutableSet set];
for (NSString *word in words) {
if ([seen containsObject:word]) {
[dups addObject:word];
}
[seen addObject:word];
}
return [dups allObjects];
}
Assuming NSSet uses hash tables behind the scenes (which I'm betting it does), this is going to be faster than the previously suggested O(n^2) solution.
Here's something off the top of my head:
NSMutableSet* duplicates = [NSMutableSet set];
NSArray* words = [NSArray arrayWithObjects:#"Apple", #"Apple", #"Orange", #"Apple", #"Orange", #"Pear", nil];
[words enumerateObjectsUsingBlock:^(NSString* str, NSUInteger idx, BOOL *stop) {
for (int i = idx + 1; i < words.count; i++) {
if ([str isEqualToString:[words objectAtIndex:i]]) {
[duplicates addObject:str];
break;
}
}
}];
NSLog(#"Dups: %#", [duplicates allObjects]); // Prints "Apple" and "Orange"
The use of an NSSet, as opposed to an NSArray, ensures strings are not added more than once. Obviously, there are optimizations that could be done, but it should be a good starting point.
I assume that you want to count appearances of words in your array and output those with a count of more than one. A basic and verbose way to do that would be:
// Make an array of words - some duplicates
NSArray *wordList = [[NSArray alloc] initWithObjects:
#"Apple", #"Banana", #"Pencil",
#"Steve Jobs", #"Kandahar",
#"Apple", #"Banana", #"Apple",
#"Pear", #"Pear", nil];
// Make an mutable dictionary - the key will be a word from the list
// and the value will be a number representing the number of times the
// word appears in the original array. It starts off empty.
NSMutableDictionary *wordCount = [[NSMutableDictionary alloc] init];
// In turn, take each word in the word list...
for (NSString *s in wordList) {
int count = 1;
// If the word is already in the dictionary
if([wordCount objectForKey:s]) {
// Increse the count by one
count = [[wordCount objectForKey:s] intValue] + 1;
}
// Save the word count in the dictionary
[wordCount setObject:[NSNumber numberWithInt:count] forKey:s];
}
// For each word...
for (NSString *s in [wordCount keysOfEntriesPassingTest:
^(id key, id obj, BOOL *stop) {
if ([obj intValue] > 1) return YES; else return NO;
}]) {
// print the word and the final count
NSLog(#"%2d %#", [[wordCount objectForKey:s] intValue], s);
}
The output would be:
3 Apple
2 Pear
2 Banana
I have an Array {-1,0,1,2,3,4...}
I am trying to find whether an element exist in these number or not, code is not working
NSInteger ind = [favArray indexOfObject:[NSNumber numberWithInt:3]];
in ind i am always getting 2147483647
I am filling my array like this
//Loading favArray from favs.plist
NSString* favPlistPath = [[NSBundle mainBundle] pathForResource:#"favs" ofType:#"plist"];
NSMutableDictionary* favPlistDict = [[NSMutableDictionary alloc] initWithContentsOfFile:favPlistPath];
NSString *favString = [favPlistDict objectForKey:#"list"];
NSArray *favList = [favString componentsSeparatedByString:#","];
//int n = [[favList objectAtIndex:0] intValue];
favArray = [[NSMutableArray alloc] initWithCapacity:100];
if([favList count]>1)
{
for(int i=1; i<[favList count]; i++)
{
NSNumber *f = [favList objectAtIndex:i];
[favArray insertObject:f atIndex:(i-1)];
}
}
That's the value of NSNotFound, which means that favArray contains no object that isEqual: to [NSNumber numberWithInt:3]. Check your array.
After second edit:
Your favList array is filled with NSString objects. You should convert the string objects to NSNumber objects before inserting them in favArray:
NSNumber *f = [NSNumber numberWithInt:[[favList objectAtIndex:i] intValue]];