I have created a NSDictionary like following :
NSArray * alphabets = [NSArray arrayWithObjects:#"a",#"b",#"c",#"d",#"e",#"f",#"g",#"h",#"i",#"j",#"k",#"l",#"m",#"n",#"o",#"p",#"q",#"r",#"s",#"t",#"u",#"v",#"w",#"x",#"y",#"z",nil];
alphaToNum = [NSMutableDictionary dictionary];
numToAlpha = [NSMutableDictionary dictionary];
for(NSString* character in alphabets)
{
[alphaToNum setObject:[NSNumber numberWithInteger:index] forKey:character];
[numToAlpha setObject:character forKey:[NSNumber numberWithInteger:index]];
index++;
}
now I want to access to "numToAlpha" like following :
NSInteger code1;
NSNumber * nn = [numToAlpha objectForKey:code1];
and I'll get error whereas in manual for objectforkey it clearly said (id)objectforkey(id) which means anything!
NSInteger is not an object. id refers to any object type. You need to use [NSNumber numberWithInteger:code1] as you are already doing in your code sample.
Related
So I have an object of type 'id friendData'stored in a singleton class 'coreData' from which I produce a mutable array for object key "data" as follows:
NSMutableArray *friends = [_coreData.friendData objectForKey:#"data"];
I then establish a dictionary which takes user parameters using keys "id" and "name", as well as a NSMutable array *scores which is obtained by a HTTP post request.
NSMutableDictionary *directory = [NSMutableDictionary dictionary];
[directory setObject:[friends valueForKey:#"id"] forKey:#"id"];
[directory setObject:[friends valueForKey:#"name"] forKey:#"name"];
[directory setObject:scores forKey:#"score"];
I am wanting to order object scores from highest to lowest for the purposes of a scoreboard, but it's my understanding that rearranging within a dictionary won't maintain the same order for the objects 'id' and 'name'. Is this infact possible, or is it better to reintroduce the *scores object to *friends under an appropriate key, and apply a sort algorith? If so, how? Any help, including example code and possible sort procedure would be great!
Just sort scores array before setting it into the dictionary. I am not sure what are exactly the kind of objects you have in scores, Im guessing they are plain NStrings. In that case this should work:
NSArray *sortedArray = [scores sortedArrayUsingComparator:^NSComparisonResult(id a, id b) {
NSInteger first = [(NSString *)a intValue];
NSDate *second = [(NSString *)b intValue];
return [first compare:second];
}];
NSMutableDictionary *directory = [NSMutableDictionary dictionary];
[directory setObject:[friends valueForKey:#"id"] forKey:#"id"];
[directory setObject:[friends valueForKey:#"name"] forKey:#"name"];
[directory setObject:sortedScoresArray forKey:#"score"];
I was going through the release notes for Xcode 4.4 and noticed this:
LLVM 4.0 Compiler
Xcode now includes the Apple LLVM Compiler version 4.0, including the following newObjective-C language features:
[...]
- Objective-C literals: create literals for NSArray, NSDictionary, and NSNumber, just the same as the literals for NSString
I'm intrigued about this feature. It's not entirely clear to me just how literals for NSString work and how one could use them on NSArray, NSDictionary, and NSNumber.
What are the details?
Copied verbatim from http://cocoaheads.tumblr.com/post/17757846453/objective-c-literals-for-nsdictionary-nsarray-and:
Objective-C literals: one can now create literals for NSArray, NSDictionary, and NSNumber (just like one can create literals for NSString)
NSArray Literals
Previously:
array = [NSArray arrayWithObjects:a, b, c, nil];
Now:
array = #[ a, b, c ];
NSDictionary Literals
Previously:
dict = [NSDictionary dictionaryWithObjects:#[o1, o2, o3]
forKeys:#[k1, k2, k3]];
Now:
dict = #{ k1 : o1, k2 : o2, k3 : o3 };
NSNumber Literals
Previously:
NSNumber *number;
number = [NSNumber numberWithChar:'X'];
number = [NSNumber numberWithInt:12345];
number = [NSNumber numberWithUnsignedLong:12345ul];
number = [NSNumber numberWithLongLong:12345ll];
number = [NSNumber numberWithFloat:123.45f];
number = [NSNumber numberWithDouble:123.45];
number = [NSNumber numberWithBool:YES];
Now:
NSNumber *number;
number = #'X';
number = #12345;
number = #12345ul;
number = #12345ll;
number = #123.45f;
number = #123.45;
number = #YES;
[Edit]
zxoq at http://news.ycombinator.com/item?id=3672744 has added more interesting new subscripting. (Added with literals):
arr[1] === [arr objectAtIndex:1]
dict[#"key"] === [dict objectForKey:#"key"]
[Edit 2]
The new ObjC literals were discussed in multiple WWDC 2012 sessions. I intentionally didn't remove the the filenames and the time of each slide so you can find them for yourself if you feel like. They are essentially the same thing as stated in this post, but there are also a few new things that I'll mention above the images.
Please note that images are all big. Simply drag them into another tab to view them in their original size
[NSNumber numberWithint:42]
[NSNumber numberWithDouble:10.8]
[NSNumber numberWithBool:YES]
[NSNumber numberWithint:6 + x * 2012]
#42
#10.8
#YES
#(6 + x * 2012)
[NSArray arrayWithObjects: a, b, c, nil]
[array objectAtIndex:i]
[NSDictionary dictionaryWithObjectsAndKeys: v1, k1, v2, k2, nil];
[dictionary valueForKey:k]
#[a, b, c]
array[i]
#{k1:v1, k2:v2}
dictionary[k]
This part is new. Expression Literals
When you have an expression (M_PI / 16 for example) you should put it inside parenthesis.
This syntax works for numeral expressions, booleans, finding an index in a (C-) string, boolean values, enum constants, and even character strings!
NSNumber *piOverSixteen = [NSNumber numberWithDouble: (M_PI / 16)];
NSNumber *hexDigit = [NSNumber numberWithChar:"0123456789ABCDEF"[i % 16]];
NSNumber *usesScreenFonts = [NSNumber numberWithBool:[NSLayoutManager usesScreenFonts]];
NSNumber *writingDirection = [NSNumber numberWithInt:NSWritingDirectionLeftToRight];
NSNumber *path = [NSString stringWithUTF8String: getenv("PATH")];
NSNumber *piOverSixteen = #( M_PI / 16 );
NSNumber *hexDigit = #( "0123456789ABCDEF"[i % 16] );
NSNumber *usesScreenFonts = #( [NSLayoutManager usesScreenFonts] );
NSNumber *writingDirection = #( NSWritingDirectionLeftToRight );
NSNumber *path = #( getenv("PATH") );
More about character strings and how/when you can use this literal syntax:
NSString *path = [NSString stringWithUTF8String: getenv("PATH")];
for (NSString *dir in [path componentsSeparatedByString: #":"]) {
// search for a file in dir...
}
NSString *path = #( getenv("PATH") );
for (NSString *dir in [path componentsSeparatedByString: #":"]) {
// search for a file in dir...
}
How array literals work
// when you write this:
array = #[a, b, c ];
// compiler generates:
id objects[] = { a, b, c };
NSUInteger count = sizeof(objects) / sizeof(id);
array = [NSArray arrayWithObjects:objects count:count];
How dictionary literals work
// when you write this:
dict = #{k1 : o1, k2 : o2, k3 : o3 };
// compiler generates:
id objects[] = { o1, o2, o3 };
id keys[] = { k1, k2, k3 };
NSUInteger count = sizeof(objects) / sizeof(id);
dict = [NSDictionary dictionaryWithObjects:objects
forKeys:keys
count:count];
More on array subscripting
#implementation SongList {
NSMutableArray *_songs;
}
- (Song *)replaceSong:(Song *)newSong atindex:(NSUinteger)idx {
Song *oldSong = [_songs objectAtIndex:idx];
[_songs replaceObjectAtindex:idx withObject:newSong];
return oldSong;
}
#implementation SongList {
NSMutableArray *_songs;
}
- (Song *)replaceSong:(Song *)newSong atindex:(NSUinteger)idx {
Song *oldSong = _songs[idx];
_songs[idx] = newSong;
return oldSong;
}
More on dictionary subscripting
#implementation Database {
NSMutableDictionary *_storage;
}
- (id)replaceObject:(id)newObject forKey:(id <NSCopying>)key {
id oldObject = [_storage objectForKey:key];
[_storage setObject:object forKey:key];
return oldObject;
}
#implementation Database {
NSMutableDictionary *_storage;
}
- (id)replaceObject:(id)newObject forKey:(id <NSCopying>)key {
id oldObject = _storage[key];
_storage[key] = newObject;
return oldObject;
}
[Edit 3]
Mike Ash has a great writeup about these new literals. If you want to know more about this stuff, make sure to check it out.
The Objective-C compiler has hardcoded knowledge of the memory layout of instances of the NSConstantString class, aka the __CFConstantString class. Check out the RewriteObjCStringLiteral function in lib/Rewrite/RewriteModernObjC.cpp in the clang source code. The compiler simply emits data that matches the layout of instances of the NSConstantString class.
There are a couple of possibilities for literal NSArray and NSDictionary instances. They could do something like what they did for literal strings - hardcode the instance layout (for a special subclass) in the compiler and emit data in that layout. Or they could have the compiler emit code that simply creates an instance at runtime.
From “Objective-C Literals”
1) NSNumber, NSDictionary and NSArray literals are available in Xcode 4.4.
2) NSDictionary and NSArray subscripting need "Xcode 4.4 and OS X 10.8 or later SDK" or "Xcode 4.5 and iOS 6 or later SDK"
Looks to me like the subscripting needs runtime support and hence won't work before iOS6.
Apple LLVM Compiler 4.0 added literal support for Objective-C. It starts from at sign #
NSNumber Literals
NSNumber *someBool = [NSNumber numberWithBool:YES];
//BOOL literal
NSNumber *someBool = #YES;
NSNumber *someChar= [NSNumber numberWithChar:'a'];
//character literal
NSNumber *someChar = #'a';
NSNumber *someInt = [NSNumber numberWithInt:1];
NSNumber *someInt = [NSNumber numberWithUnsignedInt:1U];
NSNumber *someInt = [NSNumber numberWithLong:1L];
NSNumber *someInt = [NSNumber numberWithLongLong:1LL];
//integer literal
NSNumber *someInt = #1;
NSNumber *someInt = #1U;
NSNumber *someInt = #1L;
NSNumber *someInt = #1LL;
NSNumber *someFloat = [NSNumber numberWithFloat:3.141592654F];
NSNumber *someFloat = [NSNumber numberWithDouble:3.1415926535];
//float literal
NSNumber *someFloat = #3.141592654F;
NSNumber *someFloat = #3.1415926535;
Collection Literals
NSArray *someArray = [NSArray arrayWithObjects: #"A", #"B", #"C", nil];
//array literal
NSArray *someArray = #[ #"A", #"B", #"C" ];
NSDictionary *someDict = [NSDictionary dictionaryWithObjectsAndKeys:
#"key1", #"value1",
#"key1", #"value2",
nil];
//dictionary literal
NSDictionary *someDict = #{ #"Character" : #"Zelda",
#"key1" : #"value2",
#"key2" : #value2 };
Collection Subscripting
NSString *var1 = [someArray objectAtIndex:0]; // Returns 'A'
NSString *var2 = [someDict objectForKey:#"key1"]; // Returns 'value1'
//Collection Subscripting
//read
NSString *var1 = someArray[0]; // Returns 'A'
NSString *var2 = someDict[#"key1"]; // Returns 'value1'
//write to mutable collection
someArray[0] = #"AA";
someDict[#"key1"] = #"value11";
Boxed Expressions - C-style expression into an Objective-C. Works with numbers, enums, structs
//Syntax #( <expression> )
[NSNumber numberWithInt:(INT_MAX + 1)];
//Boxed Expressions
NSNumber *var = #(INT_MAX + 1);
I was going through the release notes for Xcode 4.4 and noticed this:
LLVM 4.0 Compiler
Xcode now includes the Apple LLVM Compiler version 4.0, including the following newObjective-C language features:
[...]
- Objective-C literals: create literals for NSArray, NSDictionary, and NSNumber, just the same as the literals for NSString
I'm intrigued about this feature. It's not entirely clear to me just how literals for NSString work and how one could use them on NSArray, NSDictionary, and NSNumber.
What are the details?
Copied verbatim from http://cocoaheads.tumblr.com/post/17757846453/objective-c-literals-for-nsdictionary-nsarray-and:
Objective-C literals: one can now create literals for NSArray, NSDictionary, and NSNumber (just like one can create literals for NSString)
NSArray Literals
Previously:
array = [NSArray arrayWithObjects:a, b, c, nil];
Now:
array = #[ a, b, c ];
NSDictionary Literals
Previously:
dict = [NSDictionary dictionaryWithObjects:#[o1, o2, o3]
forKeys:#[k1, k2, k3]];
Now:
dict = #{ k1 : o1, k2 : o2, k3 : o3 };
NSNumber Literals
Previously:
NSNumber *number;
number = [NSNumber numberWithChar:'X'];
number = [NSNumber numberWithInt:12345];
number = [NSNumber numberWithUnsignedLong:12345ul];
number = [NSNumber numberWithLongLong:12345ll];
number = [NSNumber numberWithFloat:123.45f];
number = [NSNumber numberWithDouble:123.45];
number = [NSNumber numberWithBool:YES];
Now:
NSNumber *number;
number = #'X';
number = #12345;
number = #12345ul;
number = #12345ll;
number = #123.45f;
number = #123.45;
number = #YES;
[Edit]
zxoq at http://news.ycombinator.com/item?id=3672744 has added more interesting new subscripting. (Added with literals):
arr[1] === [arr objectAtIndex:1]
dict[#"key"] === [dict objectForKey:#"key"]
[Edit 2]
The new ObjC literals were discussed in multiple WWDC 2012 sessions. I intentionally didn't remove the the filenames and the time of each slide so you can find them for yourself if you feel like. They are essentially the same thing as stated in this post, but there are also a few new things that I'll mention above the images.
Please note that images are all big. Simply drag them into another tab to view them in their original size
[NSNumber numberWithint:42]
[NSNumber numberWithDouble:10.8]
[NSNumber numberWithBool:YES]
[NSNumber numberWithint:6 + x * 2012]
#42
#10.8
#YES
#(6 + x * 2012)
[NSArray arrayWithObjects: a, b, c, nil]
[array objectAtIndex:i]
[NSDictionary dictionaryWithObjectsAndKeys: v1, k1, v2, k2, nil];
[dictionary valueForKey:k]
#[a, b, c]
array[i]
#{k1:v1, k2:v2}
dictionary[k]
This part is new. Expression Literals
When you have an expression (M_PI / 16 for example) you should put it inside parenthesis.
This syntax works for numeral expressions, booleans, finding an index in a (C-) string, boolean values, enum constants, and even character strings!
NSNumber *piOverSixteen = [NSNumber numberWithDouble: (M_PI / 16)];
NSNumber *hexDigit = [NSNumber numberWithChar:"0123456789ABCDEF"[i % 16]];
NSNumber *usesScreenFonts = [NSNumber numberWithBool:[NSLayoutManager usesScreenFonts]];
NSNumber *writingDirection = [NSNumber numberWithInt:NSWritingDirectionLeftToRight];
NSNumber *path = [NSString stringWithUTF8String: getenv("PATH")];
NSNumber *piOverSixteen = #( M_PI / 16 );
NSNumber *hexDigit = #( "0123456789ABCDEF"[i % 16] );
NSNumber *usesScreenFonts = #( [NSLayoutManager usesScreenFonts] );
NSNumber *writingDirection = #( NSWritingDirectionLeftToRight );
NSNumber *path = #( getenv("PATH") );
More about character strings and how/when you can use this literal syntax:
NSString *path = [NSString stringWithUTF8String: getenv("PATH")];
for (NSString *dir in [path componentsSeparatedByString: #":"]) {
// search for a file in dir...
}
NSString *path = #( getenv("PATH") );
for (NSString *dir in [path componentsSeparatedByString: #":"]) {
// search for a file in dir...
}
How array literals work
// when you write this:
array = #[a, b, c ];
// compiler generates:
id objects[] = { a, b, c };
NSUInteger count = sizeof(objects) / sizeof(id);
array = [NSArray arrayWithObjects:objects count:count];
How dictionary literals work
// when you write this:
dict = #{k1 : o1, k2 : o2, k3 : o3 };
// compiler generates:
id objects[] = { o1, o2, o3 };
id keys[] = { k1, k2, k3 };
NSUInteger count = sizeof(objects) / sizeof(id);
dict = [NSDictionary dictionaryWithObjects:objects
forKeys:keys
count:count];
More on array subscripting
#implementation SongList {
NSMutableArray *_songs;
}
- (Song *)replaceSong:(Song *)newSong atindex:(NSUinteger)idx {
Song *oldSong = [_songs objectAtIndex:idx];
[_songs replaceObjectAtindex:idx withObject:newSong];
return oldSong;
}
#implementation SongList {
NSMutableArray *_songs;
}
- (Song *)replaceSong:(Song *)newSong atindex:(NSUinteger)idx {
Song *oldSong = _songs[idx];
_songs[idx] = newSong;
return oldSong;
}
More on dictionary subscripting
#implementation Database {
NSMutableDictionary *_storage;
}
- (id)replaceObject:(id)newObject forKey:(id <NSCopying>)key {
id oldObject = [_storage objectForKey:key];
[_storage setObject:object forKey:key];
return oldObject;
}
#implementation Database {
NSMutableDictionary *_storage;
}
- (id)replaceObject:(id)newObject forKey:(id <NSCopying>)key {
id oldObject = _storage[key];
_storage[key] = newObject;
return oldObject;
}
[Edit 3]
Mike Ash has a great writeup about these new literals. If you want to know more about this stuff, make sure to check it out.
The Objective-C compiler has hardcoded knowledge of the memory layout of instances of the NSConstantString class, aka the __CFConstantString class. Check out the RewriteObjCStringLiteral function in lib/Rewrite/RewriteModernObjC.cpp in the clang source code. The compiler simply emits data that matches the layout of instances of the NSConstantString class.
There are a couple of possibilities for literal NSArray and NSDictionary instances. They could do something like what they did for literal strings - hardcode the instance layout (for a special subclass) in the compiler and emit data in that layout. Or they could have the compiler emit code that simply creates an instance at runtime.
From “Objective-C Literals”
1) NSNumber, NSDictionary and NSArray literals are available in Xcode 4.4.
2) NSDictionary and NSArray subscripting need "Xcode 4.4 and OS X 10.8 or later SDK" or "Xcode 4.5 and iOS 6 or later SDK"
Looks to me like the subscripting needs runtime support and hence won't work before iOS6.
Apple LLVM Compiler 4.0 added literal support for Objective-C. It starts from at sign #
NSNumber Literals
NSNumber *someBool = [NSNumber numberWithBool:YES];
//BOOL literal
NSNumber *someBool = #YES;
NSNumber *someChar= [NSNumber numberWithChar:'a'];
//character literal
NSNumber *someChar = #'a';
NSNumber *someInt = [NSNumber numberWithInt:1];
NSNumber *someInt = [NSNumber numberWithUnsignedInt:1U];
NSNumber *someInt = [NSNumber numberWithLong:1L];
NSNumber *someInt = [NSNumber numberWithLongLong:1LL];
//integer literal
NSNumber *someInt = #1;
NSNumber *someInt = #1U;
NSNumber *someInt = #1L;
NSNumber *someInt = #1LL;
NSNumber *someFloat = [NSNumber numberWithFloat:3.141592654F];
NSNumber *someFloat = [NSNumber numberWithDouble:3.1415926535];
//float literal
NSNumber *someFloat = #3.141592654F;
NSNumber *someFloat = #3.1415926535;
Collection Literals
NSArray *someArray = [NSArray arrayWithObjects: #"A", #"B", #"C", nil];
//array literal
NSArray *someArray = #[ #"A", #"B", #"C" ];
NSDictionary *someDict = [NSDictionary dictionaryWithObjectsAndKeys:
#"key1", #"value1",
#"key1", #"value2",
nil];
//dictionary literal
NSDictionary *someDict = #{ #"Character" : #"Zelda",
#"key1" : #"value2",
#"key2" : #value2 };
Collection Subscripting
NSString *var1 = [someArray objectAtIndex:0]; // Returns 'A'
NSString *var2 = [someDict objectForKey:#"key1"]; // Returns 'value1'
//Collection Subscripting
//read
NSString *var1 = someArray[0]; // Returns 'A'
NSString *var2 = someDict[#"key1"]; // Returns 'value1'
//write to mutable collection
someArray[0] = #"AA";
someDict[#"key1"] = #"value11";
Boxed Expressions - C-style expression into an Objective-C. Works with numbers, enums, structs
//Syntax #( <expression> )
[NSNumber numberWithInt:(INT_MAX + 1)];
//Boxed Expressions
NSNumber *var = #(INT_MAX + 1);
here is the problem :
NSArray * alphabets = [NSArray arrayWithObjects:#"a",#"b",#"c",#"d",#"e",#"f",#"g",#"h",#"i",#"j",#"k",#"l",#"m",#"n",#"o",#"p",#"q",#"r",#"s",#"t",#"u",#"v",#"w",#"x",#"y",#"z",nil];
NSDictionary * alphaToNum = [NSDictionary dictionaryWithObject:alphabets forKey:1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26];
//I know above line meant to not work I just brought it here as an example
how can I create a dictionary just like above which is working?
You can only use objects as keys or values in a NSDictionary, so you have to use NSNumber as wrapper for your integer key.
NSMutableDictionary *alphaToNum = [NSMutableDictionary dictionary];
NSArray *alphabet = [NSArray arrayWithObjects:#"a",#"b",#"c",#"d",#"e",#"f",#"g",#"h",#"i",#"j",#"k",#"l",#"m",#"n",#"o",#"p",#"q",#"r",#"s",#"t",#"u",#"v",#"w",#"x",#"y",#"z",nil];
NSInteger index = 0;
for(NSString *character in alphabet)
{
index ++;
[alphaToNum setObject:character forKey:[NSNumber numberWithInteger:index]];
}
I have gone through following question.
Convert NSString to NSDictionary
It is something different then my question.
My question is as follows.
NSString *x=#"<Category_Id>5</Category_Id><Category_Name>Motos</Category_Name><Category_Picture>http://192.168.32.20/idealer/admin/Picture/icon_bike2009819541578.png</Category_Picture>";
Now I want to convert this into a dictionary, something like this,
dictionary key = Category_Id | value = 5
dictionary key = Category_Name | value = ???
dictionary key = Category_Picture | value = ???
I don't know how to perform this.
Not the fastest implementation, but this would do the trick (and doesn’t require any third party libraries):
#interface NSDictionary (DictionaryFromXML)
+ (NSDictionary *)dictionaryFromXML:(NSString *)xml;
#end
#implementation NSDictionary (DictionaryFromXML)
+ (NSDictionary *)dictionaryFromXML:(NSString *)xml
{
// We need to wrap the input in a root element
NSString *x = [NSString stringWithFormat:#"<x>%#</x>", xml];
NSXMLDocument *doc = [[[NSXMLDocument alloc] initWithXMLString:x
options:0
error:NULL]
autorelease];
if (!doc)
return nil;
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
for (NSXMLElement *el in [[doc rootElement] children])
[dict setObject:[el stringValue] forKey:[el name]];
return dict;
}
#end
If it's XML then you can use an NSXMLParser. If it's not then you can write your own parser.
You could do it with a regular expression... Something like <([^>]+)>([^<]+)</\1> would grab the key into capture 1 and the value into capture 2. Iterate over the matches and build the dictionary.
This uses RegexKitLite:
NSString * x = #"<Category_Id>5</Category_Id><Category_Name>Motos</Category_Name><Category_Picture>http://192.168.32.20/idealer/admin/Picture/icon_bike2009819541578.png</Category_Picture>";
NSString * regex = #"<([^>]+)>([^<]+)</\\1>";
NSArray * cap = [x arrayOfCaptureComponentsMatchedByRegex:regex];
NSMutableDictionary * d = [NSMutableDictionary dictionary];
for (NSArray * captures in cap) {
if ([captures count] < 3) { continue; }
NSString * key = [captures objectAtIndex:1];
NSString * value = [captures objectAtIndex:2];
[d setObject:value forKey:key];
}
NSLog(#"%#", d);