I have a NSMutableArray which contains a few NSString objects. How can I test if the array contains a particular string literal?
I tried [array containsObject:#"teststring"] but that doesn't work.
What you're doing should work fine. For example
NSArray *a = [NSArray arrayWithObjects:#"Foo", #"Bar", #"Baz", nil];
NSLog(#"At index %i", [a indexOfObject:#"Bar"]);
Correctly logs "At index 1" for me. Two possible foibles:
indexOfObject sends isEqual messages to do the comparison - you've not replaced this method in a category?
Make sure you're testing against NSNotFound for failure to locate, and not (say) 0.
[array indexOfObject:object] != NSNotFound
Comparing against string literals only works in code examples. In the real world you often need to compare against NSString* instances in e.g. an array, in which case containsObject fails because it compares against the object, not the value.
You could add a category to your implementation which extends NS(Mutable)Array with a method to check wether it contains the string (or whatever other type you need to compare against);
#implementation NSMutableArray (ContainsString)
-(BOOL) containsString:(NSString*)string
{
for (NSString* str in self) {
if ([str isEqualToString:string])
return YES;
}
return NO;
}
#end
You may also use a predicate:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF IN %#", theArray];
BOOL result = [predicate evaluateWithObject:theString];
for every object
[(NSString *) [array objectAtIndex:i] isEqualToString:#"teststring"];
Related
I am using a NSPredicate to search numbers in the list using UISearchBar ,
it works in case of strings but does not work for an integer
I am using the following predicate
predicate = [NSPredicate predicateWithFormat:[NSString stringWithFormat:#"%# contains[c] %d", #"number", [searchBar.text intValue]]];
[objectArray filterUsingPredicate:predicate];
[tableview reloadData];
FOR example if I type 1 then all the ones in the array must be listed, I have tried == it works only for the exact number if tried any work around for this any body?
Now I get an error if I use this method "Can't use in/contains operator with collection"
I think this predicate should work for you:
predicate = [NSPredicate predicateWithFormat:#"self.number.stringValue CONTAINS %#",searchBar.text];
After thinking about this, I'm not sure why self.number.stringValue works, but it did when I tested it (self.number is an int). Not sure why I can send stringValue to an int?
Predicates can be tricky to work with, so perhaps an alternative would work for you:
NSInteger index = 0;
while (index < objectArray.count)
{
NSString *currentString = [objectArray objectAtIndex:index];
if ([currentString rangeOfString:searchBar.text].length == 0)
{
[objectArray removeObjectAtIndex:index];
continue;
}
index++;
}
Here, any strings in your array that do not contain your searchBar text will be removed.
I want to get the index of an object within the NSMutableArray of categories.
The category object has an attribute "category_title" and I want to be able to get the index by passing the value of category_title.
I have looked through the docs and can't find a simple way to go about this.
NSArray does not guarantee that you can only store one copy of a given object, so you have to make sure that you handle that yourself (or use NSOrderedSet).
That said, there are a couple approaches here. If your category objects implement isEqual: to match category_title, then you can just use -indexOfObject:.
If you can't do that (because the category objects use a different definition of equality), use -indexOfObjectPassingTest:. It takes a block in which you can do whatever test you want to define your "test" - in this case, testing category_title string equality.
Note that these are all declared for NSArray, so you won't see them if you are only looking at the NSMutableArray header/documentation.
EDIT: Code sample. This assumes objects of class CASCategory with an NSString property categoryTitle (I can't bring myself to put underscores in an ivar name :-):
CASCategory *cat1 = [[CASCategory alloc] init];
[cat1 setCategoryTitle:#"foo"];
CASCategory *cat2 = [[CASCategory alloc] init];
[cat2 setCategoryTitle:#"bar"];
CASCategory *cat3 = [[CASCategory alloc] init];
[cat3 setCategoryTitle:#"baz"];
NSMutableArray *array = [NSMutableArray arrayWithObjects:cat1, cat2, cat3, nil];
[cat1 release];
[cat2 release];
[cat3 release];
NSUInteger barIndex = [array indexOfObjectPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
if ([[(CASCategory *)obj categoryTitle] isEqualToString:#"bar"]) {
*stop = YES;
return YES;
}
return NO;
}];
if (barIndex != NSNotFound) {
NSLog(#"The title of category at index %lu is %#", barIndex, [[array objectAtIndex:barIndex] categoryTitle]);
}
else {
NSLog(#"Not found");
}
Not sure that I understand the question but something like this might work (assuming the Mutable Array contains objects of Class "Category"):
int indx;
bool chk;
for (Category *aCategory in theArray)
{
chk = ([[aCategory category_title] isEqualToString:#"valOfCategoryTitle"])
if ( chk )
indx = [theArray indexOfObject:aCategory];
}
Try this code much more simpler:-
int f = [yourArray indexOfObject:#"yourString"];
I am not sure how to go about this. I have an NSMutableArray (addList) which holds all the items to be added to my datasource NSMutableArray.
I now want to check if the object to be added from the addList array already exists in the datasource array. If it does not exist add the item, if exists ignore.
Both the objects have a string variable called iName which i want to compare.
Here is my code snippet
-(void)doneClicked{
for (Item *item in addList){
/*
Here i want to loop through the datasource array
*/
for(Item *existingItem in appDelegate.list){
if([existingItem.iName isEqualToString:item.iName]){
// Do not add
}
else{
[appDelegate insertItem:item];
}
}
}
But i find the item to be added even if it exists.
What am i doing wrong ?
There is a very useful method for this in NSArray i.e. containsObject.
NSArray *array;
array = [NSArray arrayWithObjects: #"Nicola", #"Margherita", #"Luciano", #"Silvia", nil];
if ([array containsObject: #"Nicola"]) // YES
{
// Do something
}
I found a solution, may not be the most efficient of all, but atleast works
NSMutableArray *add=[[NSMutableArray alloc]init];
for (Item *item in addList){
if ([appDelegate.list containsObject:item])
{}
else
[add addObject:item];
}
Then I iterate over the add array and insert items.
Use NSPredicate.
NSArray *list = [[appDelegate.list copy] autorelease];
for (Item *item in addList) {
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"iName MATCHES %#", item.iName];
NSArray *filteredArray = [list filteredArrayUsingPredicate:predicate];
if ([filteredArray count] > 0) [appDelegate insertItem:item];
}
Did you try indexOfObject:?
-(void)doneClicked{
for (Item *item in addList){
if([appDelegate.list indexOfObject:item] == NSNotFound){
[appDelegate insertItem:item];
}
}
UPDATE: You have a logical mistake, not mistake in code. assume the first array is ['a', 'b', 'c'], and the second is ['a', 'x', 'y', 'z']. When you iterate with 'a' through the second array it won't add 'a' to second array in the first iteration (compare 'a' with 'a') but will add during the second (compare 'a' with 'x'). That is why you should implement isEqual: method (see below) in your 'Item' object and use the code above.
- (BOOL)isEqual:(id)anObject {
if ([anObject isKindOfClass:[Item class]])
return ([self.iName isEqualToString:((Item *)anObject).iName]);
else
return NO;
}
Have a look at NSSet. You can add objects and the object will only be added if the object is unique. You can create a NSSet from an NSArray or vise versa.
You can override isEquals and hash on the object so that it returns a YES / NO based on the comparison of the iName property.
Once you have that you can use...
- (void)removeObjectsInArray:(NSArray *)otherArray
To clean the list before adding all the remaining objects.
NR4TR said correctly but i think one break statement is sufficient
if([existingItem.iName isEqualToString:item.iName]){
// Do not add
break;
}
Convert Lowercase and Trim whitespace and then check..
[string lowercaseString];
and
NSString *trim = [string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
You compare the addList's first object and appDelegate.list's first object, if they are not equal, you insert the addList's object. The logic is wrong, you should compare one addList's object with every appDelegate.list's object.
I have an NSArray of objects, which has a particular property called name (type NSString).
I have a second NSArray of NSStrings which are names.
I'd like to get an NSArray of all the objects whose .name property matches one of the names in the second NSArray.
How do I go about this, fast and efficiently as this will be required quite often.
Why not just to use predicates to do that for you?:
// For number kind of values:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF = %#", value];
NSArray *results = [array_to_search filteredArrayUsingPredicate:predicate];
// For string kind of values:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF contains[cd] %#", value];
NSArray *results = [array_to_search filteredArrayUsingPredicate:predicate];
// For any object kind of value (yes, you can search objects also):
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"SELF MATCHES %#", value];
NSArray *results = [array_to_search filteredArrayUsingPredicate:predicate];
Here's a simple way:
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"name == %#", nameToFind];
[listOfItems filteredArrayUsingPredicate:predicate];
With your current data structures, you can only do it in O(n^2) time by looping over the first array once for each member of the second array:
NSMutableArray * array = [NSMutableArray array];
for (NSString * name in names) {
for (MyObject * object in objects) {
if ([[myObject name] isEqualToString:name]) {
[array addObject:object];
}
}
}
(Alternate as suggested by Stefan: loop over the objects array and ask the names array if it containsObject: for the name of each object.)
But if this really needs to be faster (really depends on the size of the arrays as much as how often you do it), you can improve this by introducing an NSDictionary that maps the names in the first array to their objects. Then each of those lookups is O(1) and the overall time is O(n). (You'd have to keep this dictionary always in sync with the array of objects, which isn't hard with reasonable accessors. This technique also has the constraint that the same name can't appear on more than one object.)
An alternate way of getting this result (and which doesn't have that last constraint) is to use an NSSet for your second collection, then walk through the objects array calling containsObject: with each one on the set of names. Whether this technique is better depends on whether your two collections are roughly the same size, or if one is much larger than the other.
I like to use this method:
NSIndexSet *indexes = [_items indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
return ((MyObject *)obj).name isEqualToString:name];
}];
if (indexes.count != 0) {
//extract your objects from the indexSet, and do what you like...
}
NSMutableArray * foundNames = [NSMutableArray array];
for (MyObject * objectWithName in objectCollection) {
if ([names containsObject:objectWithName.name]) {
[foundNames objectWithName];
}
}
The methods most helpful will be:
filteredArrayUsingPredicate:
and
indexesOfObjectsPassingTest:
The second one uses a code block, not available on iOS before 4.0
Both of these will be more efficient than iterating directly.
There's a good example here:
http://developer.apple.com/library/ios/#documentation/cocoa/Conceptual/Blocks/Articles/bxUsing.html
NSMutableArray* solutions = [NSMutableArray array];
for (Object* object in objects){
for (NSString* name in names){
if ([object.name isEqualToString:name]){
[solutions addObject:object];
break; // If this doesnt work remove this
}
}
}
int count=0;
if (range.location!=NSNotFound)
{
[searchindex addObject:[NSString stringWithFormat:#"%d",count]];
}
Hello I have an array of persons, and i am trying to sort them by age using a sort descriptor.
The age field in a patient is a string so when calling:
ageSorter = [[NSSortDescriptor alloc] initWithKey:#"age" ascending:YES];
[personList sortUsingDescriptors:[NSArray arrayWithObject:ageSorter]];
It sorts them but 100 appears first because its is not using numericSearch in the compare options.
Is there a ways i can still sort with descriptor but maybe using a selector to change how to compare the strings?
The finderSortWithLocale method (both these are taken from apple api):
int finderSortWithLocale(Person *person1, Person *person2, void *locale)
{
static NSStringCompareOptions comparisonOptions = NSNumericSearch;
NSRange string1Range = NSMakeRange(0, [string1 length]);
NSString *age1 = person1.age;
NSString *age2 = person2.age;
return [age1 compare:age2
options:comparisonOptions
range:string1Range
locale:(NSLocale *)locale];
}
How to call this method (edited: call the function on array of Persons):
NSArray *sortedArray = [personList sortedArrayUsingFunction:finderSortWithLocale
context:[NSLocale currentLocale]];
I also faced the same issue and found answer here.
Instead of NSString comparison, do with your object property. i.e for age.
Example. : In ascending order :
NSArray *sortedArray = [_arrayCaptureLeadList sortedArrayUsingComparator:^(Person *obj1, Person *obj2) {
return [obj1.age compare:obj2.age options:NSNumericSearch];
}];
NSMutableArray *filterResultArray = [NSMutableArray arrayWithArray:sortedArray];
In descending order :
NSArray *sortedArray = [_arrayCaptureLeadList sortedArrayUsingComparator:^(Person *obj1, Person *obj2) {
return [obj2.age compare:obj1.age options:NSNumericSearch];
}];
NSMutableArray *filterResultArray = [NSMutableArray arrayWithArray:sortedArray];
I know this is very late to reply your question but may this will be helpful for others. ^_^
You could create a category on NSString that adds a method numericCompare: and which calls [self compare:otherString options:NSNumericSearch]. Another option is to convert the age field into a NSNumber instead of a NSString. Yet another option involves a NSComparator block and sortUsingComparator.