问题
I have an Object that contains many pieces of information, a Title String, Date String, and NSArray, amongst others. This Object has 8 different sets of this information. I want to find out which Set's Title has the most occurrences of the word "Sunday". After the data loads, I run some calculations:
NSArray *yourArrayhere = self.theObject[@"DatesSuggested"];
int occurrences = 0;
for(NSString *string in yourArrayhere){
occurrences += ([string isEqualToString:@"Sunday"]?1:0); //certain object is @"Sunday"
}
NSLog(@"number of occurences %d", occurrences);
In Console, it gives me a printout of the number of times Sunday is found in each NSArray from that Object's 8 sets. How would I then best go about getting the title for the Set in the Object that contains the most occurrences?
Each set in the Object appears like this in the console:
<Activities: 0x7fc3abe107a0, objectId: 6eUXy9SkZK, localId: (null)> {
DatesSuggested = (
Sunday,
Sunday
);
Title = Train;
VotesAgainst = 0;
VotesFor = 0;
}
Here's the entire Console Log for the PFObject:
2016-06-23 22:51:10.399 Roll 'Em Up[1675:150331] Bar D
2016-06-23 22:51:10.400 Roll 'Em Up[1675:150331] <Activities: 0x7fb33a61f190, objectId: NZ1JNtDoIR, localId: (null)> {
DatesSuggested = (
);
Title = "Bar D";
VotesAgainst = 0;
VotesFor = 1;
}
2016-06-23 22:51:10.402 Roll 'Em Up[1675:150331] Creede Trip
2016-06-23 22:51:10.402 Roll 'Em Up[1675:150331] <Activities: 0x7fb33a620650, objectId: VAu5qpGYLk, localId: (null)> {
Title = "Creede Trip";
VotesAgainst = 0;
VotesFor = 0;
}
2016-06-23 22:51:10.403 Roll 'Em Up[1675:150331] Durango Shopping
2016-06-23 22:51:10.403 Roll 'Em Up[1675:150331] <Activities: 0x7fb33a620b10, objectId: sCKWlnI3Z7, localId: (null)> {
Title = "Durango Shopping";
VotesAgainst = 0;
VotesFor = 0;
}
2016-06-23 22:51:10.404 Roll 'Em Up[1675:150331] Fishing
2016-06-23 22:51:10.404 Roll 'Em Up[1675:150331] <Activities: 0x7fb33a621310, objectId: Qy4zmA7jir, localId: (null)> {
Title = Fishing;
VotesAgainst = 0;
VotesFor = 0;
}
2016-06-23 22:51:10.405 Roll 'Em Up[1675:150331] Ouray Trip
2016-06-23 22:51:10.406 Roll 'Em Up[1675:150331] <Activities: 0x7fb33a621880, objectId: Nmrw405JZo, localId: (null)> {
Title = "Ouray Trip";
VotesAgainst = 0;
VotesFor = 0;
}
2016-06-23 22:51:10.407 Roll 'Em Up[1675:150331] Pagosa Shopping
2016-06-23 22:51:10.407 Roll 'Em Up[1675:150331] <Activities: 0x7fb33a621df0, objectId: ws0UbFwTtZ, localId: (null)> {
Title = "Pagosa Shopping";
VotesAgainst = 0;
VotesFor = 0;
}
2016-06-23 22:51:10.408 Roll 'Em Up[1675:150331] Rapids
2016-06-23 22:51:10.408 Roll 'Em Up[1675:150331] <Activities: 0x7fb33a622300, objectId: UUxHmqYOM9, localId: (null)> {
Title = Rapids;
VotesAgainst = 0;
VotesFor = 0;
}
2016-06-23 22:51:10.409 Roll 'Em Up[1675:150331] Train
2016-06-23 22:51:10.410 Roll 'Em Up[1675:150331] <Activities: 0x7fb33a622870, objectId: 6eUXy9SkZK, localId: (null)> {
DatesSuggested = (
);
Title = Train;
VotesAgainst = 0;
VotesFor = 0;
}
UPDATE:
The code I use to get the PFObject and populate table is:
- (PFQuery *)queryForTable {
PFQuery *query = [PFQuery queryWithClassName:@"Activities"];
// If no objects are loaded in memory, we look to the cache first to fill the table
// and then subsequently do a query against the network.
if (self.objects.count == 0) {
query.cachePolicy = kPFCachePolicyNetworkOnly;
}
[query orderByAscending:@"Title"];
return query;
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
// Customize the number of rows in the table view.
// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath
object:(PFObject *)object
{
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
}
self.theObject = object;
//Code for the Cell Text removed for brevity
[self performCalculations];
return cell;
}
回答1:
You've written a function that counts occurrances of an object. Just generalize it a bit...
- (NSInteger)occurrencesOf:(NSString *)string inArray:(NSArray *)array {
NSInteger occurrences = 0;
for(NSString *s in array){
occurrences += ([s isEqualToString:string]?1:0);
}
NSLog(@"number of occurences %d", occurrences);
return occurrences;
}
Put the object's arrays you want to test into an array, like this:
NSArray *arrays = @[object.array0, object.array1, ... .array8];
The pattern to maximize a function is to set an impossibly low max, and record the parameter that exceeds it...
NSArray *maxOccurrenceArray = nil;
NSInteger maxOccurrences = -LONG_MAX;
for (NSArray *array in arrays) {
NSInteger occurrences = [self occurrencesOf:@"Sunday" inArray:array];
if (occurrences > maxOccurrences) {
maxOccurrences = occurrences;
maxOccurrenceArray = array;
}
}
NSLog(@"The array with the most occurrences is %@", maxOccurrenceArray);
EDIT I'd advise getting out of the PFQueryTableVC for this test -- and, really, abandoning it altogether. It's a "convenience" class that will get in your way, ultimately. I understand for now that its a head-start, and you may not know enough yet to do without it.
Anyway, in viewWillAppear, just do this:
[super viewWillAppear:animated];
PFQuery *query = [self queryForTable];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
NSLog(@"this should be all of the objects %@", objects];
// now just run the code I suggest, adapting objects as the array of arrays
NSArray *maxOccurrenceArray = nil;
NSInteger maxOccurrences = -LONG_MAX;
for (PFObject *pfObject in objects) {
NSArray *array = [pfObject objectForKey:@"THE_NAME_OF_THE_ARRAY_PROPERTY"];
NSInteger occurrences = [self occurrencesOf:@"Sunday" inArray:array];
if (occurrences > maxOccurrences) {
maxOccurrences = occurrences;
maxOccurrenceArray = array;
}
}
NSLog(@"The array with the most occurrences is %@", maxOccurrenceArray);
}];
来源：https://stackoverflow.com/questions/38005185/which-objects-array-has-most-of-particular-object