i have a NSArray created with a Dictionary:
aMapData = [[NSMutableArray alloc] initWithCapacity:sizeof(jsonResponse)];
for (NSMutableDictionary *dict in jsonResponse) {
NSDictionary *row = [NSDictionary dictionaryWithObjectsAndKeys:[dict objectForKey:#"pID"], #"pID", [dict objectForKey:#"Address"], #"Address", nil];
[aMapData addObject:row];
}
It has about 100 rows.
I want to get the pID column, is the only option the iteration and:
[aMapData objectAtIndex:0]
?
Thank you in advance!
I found it, is not necessary an array:
NSArray *idPath = [aMapData valueForKey:#"pID"];
Yes. Otherwise you have to store each column in a separate array.
pID = [[NSMutableArray alloc] init];
address = [[NSMutableArray alloc] init];
for (NSMutableDictionary *dict in jsonResponse) {
[pID addObject:[dict objectForKey:#"pID"]];
[address addObject:[dict objectForKey:#"address"]];
}
Related
Noob here. I recently started working with objective C, and currently I am stuck with dictionary concept. I want to create a json object as shown below:
{"UserData": {
"Name": Mike Smith,
"Age": 32,
"category": [1,2,3],
"Weekly Data": [
{"Monday" : [1.0,2.0,3.0]},
{"Tuesday": [1.0,2.0,3.0]}
]
}
}
I wrote the following piece of code which doesn't give the desired result. I wonder if someone could help me.
-(NSString*)populateUserPreferences
{
NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
NSMutableArray *categorydata = [[NSMutableArray alloc] init];
NSMutableArray *weeklydata = [[NSMutableArray alloc] init];
for (int i=0;i<4; i++)
{
[categorydata addObject:[NSNumber numberWithInt:i]];
}
NSMutableArray *mondaydata = [[NSMutableArray alloc] init];
for (int j=0; j<3; j++)
{
[mondaydata addObject:[NSNumber numberWithInt:j]];
}
NSMutableArray *tuesdaydata = [[NSMutableArray alloc] init];
for (int j=0; j<3; j++)
{
[tuesdaydata addObject:[NSNumber numberWithInt:j]];
}
NSDictionary *monday = [NSDictionary dictionaryWithObject:mondaydata];
NSDictionary *tuesday = [NSDictionary dictionaryWithObject:tuesdaydata];
[weeklydata addObject: monday ];
[weeklydata addObject: tuesday ];
}
[dict setObject:[NSString stringWithFormat:"Mike Smith"] forKey:#"Name"];
[dict setObject:[NSNumber numberWithInteger:32.0] forKey:#"Age"];
[dict setObject:categorydata forKey:#"category"];
[dict setObject:weeklydata forKey:#"Weekly Data"];
NSString * userdata = [dict JSONRepresentation];
NSLog(request);
NSDictionary *userdataJson = [NSDictionary dictionaryWithObject:dict forKey:#"userData"];
return [userdataJson JSONRepresentation];
}
Thanks in advance for looking into it.
Apoorva
The mistake is when creating the monday and tuesday dictionary.
// mondaydata & tuesday is just array.
NSDictionary *monday = [NSDictionary dictionaryWithObject:mondaydata];
NSDictionary *tuesday = [NSDictionary dictionaryWithObject:tuesdaydata];
This code is mistake since you did not assign the dictionary properly (where is the key for the dictionary?). Instead you should do:
NSDictionary *mondayDict = [[NSDictionary alloc] init];
[mondayDict setObject:mondaydata forKey:"Monday"];
NSDictionary *tuesdayDict = [[NSDictionary alloc] init];
[tuesdayDict setObject:tuesdaydata forKey:"Tuesday"];
Then you can add mondayDict and tuesdayDict to your array weeklydata.
ps. just a note, name your variable meaningfully. For example, mondaydata is not descriptive enough. You should use mondayArr for example. To easily identify it is an array. Just a normal coding practice to share.
NSDictionary * dict = #{#"UserData": #{
#"Name": #"Mike Smith",
#"Age": #32,
#"category": #[#1,#2,#3],
#"Weekly Data": #[
#{#"Monday" : #[#1.0,#2.0,#3.0]},
#{#"Tuesday": #[#1.0,#2.0,#3.0]}
]
}
};
NSError * error = nil;
NSData * data = [NSJSONSerialization dataWithJSONObject:dict options:NSJSONWritingPrettyPrinted error:&error];
if (error) {
NSLog(#"%#", [error localizedDescription]);
} else {
// Do what you want
}
I have an iPad that reads data from an SQL database. The following code works fine and retrieves 2 fields from each record and reads them into an NSArray.
I now need to read 5 of the fields and I can't help but think that there is a better way of doing it rather than running 5 separate queries through php (the getinfo.php file with the choice parameter set to pick the different fields).
Any pointers to a better method for doing this?
NSString *strURLClass = [NSString stringWithFormat:#"%#%#", #"http://wwwaddress/getinfo.php?choice=1&schoolname=",obsSchoolName];
NSArray *observationsArrayClass = [[NSMutableArray alloc] initWithContentsOfURL:[NSURL URLWithString:strURLClass]];
observationListFromSQL = [[NSMutableArray alloc]init];
NSEnumerator *enumForObsClass = [observationsArrayClass objectEnumerator];
NSString *strURLDate = [NSString stringWithFormat:#"%#%#", #"http://wwwaddress/getinfo.php?choice=5&schoolname=",obsSchoolName];
NSArray *observationsArrayDate = [[NSMutableArray alloc] initWithContentsOfURL:[NSURL URLWithString:strURLDate]];
observationListFromSQL = [[NSMutableArray alloc]init];
NSEnumerator *enumForObsDate = [observationsArrayDate objectEnumerator];
id className, dateOfObs;
while (className = [enumForObsClass nextObject])
{
dateOfObs = [enumForObsDate nextObject];
[observationListFromSQL addObject:[NSDictionary dictionaryWithObjectsAndKeys:className, #"obsClass", dateOfObs, #"obsDate",nil]];
}
Yes, you can do that with less code by "folding" the statements into a loop, and using a mutable dictionary:
// Add other items that you wish to retrieve to the two arrays below:
NSArray *keys = #[#"obsClass", #"obsDate"]; // Key in the dictionary
NSArray *choices = #[#1, #5]; // Choice in the URL string
NSMutableArray *res = [NSMutableArray array];
NSMutableArray *observationListFromSQL = [NSMutableArray array];
for (int i = 0 ; i != keys.count ; i++) {
NSNumber *choice = choices[i];
NSString *strURLClass = [NSString stringWithFormat:#"http://wwwaddress/getinfo.php?choice=%#&schoolname=%#", choice, obsSchoolName];
NSArray *observationsArray = [[NSMutableArray alloc] initWithContentsOfURL:[NSURL URLWithString:strURLClass]];
NSEnumerator *objEnum = [observationsArrayClass objectEnumerator];
NSString *key = keys[i];
NSMutableDictionary *dict;
if (res.count < i) {
dict = res[i];
} else {
dict = [NSMutableDictionary dictionary];
[res addObject:dict];
}
id item;
while (item = [objEnum nextObject]) {
[res setObject:item forKey:key];
}
}
I have arrays of names and images like below
NSArray *names = [[NSArray alloc] initWithObjects:#"naveen", #"kumar",nil];
NSArray *images = [[NSArray alloc] initWithObjects:[UIImage imageNamed:#"1.jpg"], [UIImage imageNamed:#"2.jpg"], nil];
I want to create a dictionary in the following format
list:
item 0 : naveen
1.jpg
item 1: kumar
2.jpg
How can i create this one? Please?
You need to do like this :
NSMutableDictionary *nameImageDict=[NSMutableDictionary new];
for (NSInteger i=0; i<names.count; i++) {
NSArray *array=#[names[i],images[i]];
//or in older compiler 4.3 and below
//NSArray *array=[NSArray arrayWithObjects:[names objectAtIndex:i],[images objectAtIndex:i], nil];
[nameImageDict setObject:array forKey:[NSString stringWithFormat:#"item %d",i]];
}
for key item 0: it will have an array. The array contains name and image.
Like this:
NSDictionary *dictionary = [[NSDictionary alloc] initWithObjects:images andKeys:names];
Like this
NSDictionary * list = [NSDictionary dictionaryWithObjects:images forKeys:names];
I have a NSMutableArray and it has the users high scores saved into it. I want to arrange the items numerically (the numbers are stored in NSStrings.)Example:4,2,7,8To2,4,7,8What is the simplest way to do this if the data is stored in NSStrings?
This code will do it:
//creating mutable array
NSMutableArray *myArray = [NSMutableArray arrayWithObjects:#"4", #"2", #"7", #"8", nil];
//sorting
[myArray sortUsingComparator:^NSComparisonResult(NSString *str1, NSString *str2) {
return [str1 compare:str2 options:(NSNumericSearch)];
}];
//logging
NSLog(#"%#", myArray);
It uses blocks, make sure your target OS supports that (It's 4.0 for iOS and 10.6 for OSX).
This code works. I tried it:
NSMutableArray *unsortedHighScores = [[NSMutableArray alloc] initWithObjects:#"4", #"2", #"7", #"8", nil];
NSMutableArray *intermediaryArray = [[NSMutableArray alloc] init];
for(NSString *score in unsortedHighScores){
NSNumber *scoreInt = [NSNumber numberWithInteger:[score integerValue]];
[intermediaryArray addObject:scoreInt];
}
NSArray *sortedHighScores = [intermediaryArray sortedArrayUsingSelector:#selector(compare:)];
NSLog(#"%#", sortedHighScores);
The output is this:
2
4
7
8
If you have any questions about the code, just ask in the comments. Hope this helps!
The NSMutableArray method sortUsingSelector: should do it:
[scoreArray sortUsingSelector:#selector(localizedCaseInsensitiveCompare:)]
should do it.
If the array is of nsdictionaries conaining numeric value for key number
isKeyAscending = isKeyAscending ? NO : YES;
[yourArray sortUsingComparator:^NSComparisonResult(NSDictionary *obj1, NSDictionary *obj2) {
NSString *str1 = [obj1 objectForKey:#"number"];
NSString *str2 = [obj2 objectForKey:#"number"];
if(isKeyAscending) { //ascending order
return [str1 compare:str2 options:(NSNumericSearch)];
} else { //descending order
return [str2 compare:str1 options:(NSNumericSearch)];
}
}];
//yourArray is now sorted
The answer from Darshit Shah make it smootly
NSSortDescriptor *descriptor = [[NSSortDescriptor alloc]initWithKey:#"rank" ascending:YES selector:#selector(localizedStandardCompare:)];
I am a bit confused as to how arrays are handled in Objective-C.
If I have an array such as
NSarray *myArray = [[NSArray alloc]
initWithObjects:#"N", #"N", #"N", #"N", #"N",
nil];
how do I change the first occurrence to "Y"?
You need an NSMutableArray ..
NSMutableArray *myArray = [[NSMutableArray alloc]
initWithObjects:#"N", #"N", #"N", #"N", #"N",
nil];
and then
[myArray replaceObjectAtIndex:0 withObject:#"Y"];
You can't, because NSArray is immutable. But if you use NSMutableArray instead, then you can. See replaceObjectAtIndex:withObject::
[myArray replaceObjectAtIndex:0 withObject:#"Y"]
Write a helper method
-(NSArray *)replaceObjectAtIndex:(int)index inArray:(NSArray *)array withObject:(id)object {
NSMutableArray *mutableArray = [array mutableCopy];
mutableArray[index] = object;
return [NSArray arrayWithArray:mutableArray];
}
Now you can test this method with
NSArray *arr = #[#"a", #"b", #"c"];
arr = [self replaceObjectAtIndex:1 inArray:arr withObject:#"d"];
logObject(arr);
This outputs
arr = (
a,
d,
c
)
You can use similar method for NSDictionary
-(NSDictionary *)replaceObjectWithKey:(id)key inDictionary:(NSDictionary *)dict withObject:(id)object {
NSMutableDictionary *mutableDict = [dict mutableCopy];
mutableDict[key] = object;
return [NSDictionary dictionaryWithDictionary:mutableDict];
}
You can test it with
NSDictionary *dict = #{#"name": #"Albert", #"salary": #3500};
dict = [self replaceObjectWithKey:#"salary" inDictionary:dict withObject:#4400];
logObject(dict);
which outputs
dict = {
name = Albert;
salary = 4400;
}
You could even add this as a category and have it easily available.