I'm trying to write in an array, but I have the problem "NSInvalidArgumentException"
I'm beginning in objective C.
Here's a part of my code :
int charIndex;
unichar testChar1, testChar2;
NSString *valeur1, *valeur2;
NSMutableArray* tableau1 = [NSMutableArray arrayWithCapacity:4];
NSMutableArray* tableau2 = [NSMutableArray arrayWithCapacity:4];
for(charIndex=0; charIndex < 4; charIndex++) {
testChar1 = [_saisie.text characterAtIndex:charIndex];
testChar2 = [[NSString stringWithFormat:#"%d", nombreChoisi] characterAtIndex:charIndex];
NSLog(#"%C", testChar1);
valeur1 = [NSString stringWithFormat:#"%C", testChar1];
valeur2 = [NSString stringWithFormat:#"%C", testChar2];
[tableau1 replaceObjectAtIndex:charIndex withObject:valeur1];
[tableau2 replaceObjectAtIndex:charIndex withObject:valeur2];
}
Everything is working until the line 14, where the variable valeur1 take the value nil. I don't know where the problem is.
Edit : The line NSLog was just here to test the { #"%C", value } and it works. The value "nombreChoisi" is chosen before with a random function, and "_saisie.text" comes from a text field.
It looks like you are using a capital %C when building valeur1 and valeur2. Shouldn't you be using a lower case %c?
I have this code who chunks a string existing inside a NSString into a NSMutableArray:
NSString *string = #"one/two/tree";
NSMutableArray *parts = [[string componentsSeparatedByString:#"/"] mutableCopy];
NSLog(#"%#-%#-%#",parts[0],parts[1],parts[2]);
This command works perfectly but if the NSString is not obeying this pattern (not have the symbol '/' within the string), the app will crash.
How can I check if it is possible to break the NSString, preventing the app does not crash?
Just check parts.count if you don't have / in your string (or only one), you won't get three elements.
NSString *string = #"one/two/tree";
NSMutableArray *parts = [[string componentsSeparatedByString:#"/"] mutableCopy];
if(parts.count >= 3) {
NSLog(#"%#-%#-%#",parts[0],parts[1],parts[2]);
}
else {
NSLog(#"Not found");
}
From the docs:
If list has no separators—for example, "Karin"—the array contains the string itself, in this case { #"Karin" }.
https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/Reference/NSString.html#//apple_ref/occ/instm/NSString/componentsSeparatedByString:
You might be better off using the "opposite" function to put it back together...
NSString *string = #"one/two/three";
NSArray *parts = [string componentsSeparatedByString:#"/"];
NSString *newString = [parts componentsJoinedByString:#"-"];
// newString = #"one-two-three"
This will take the original string. Split it apart and then put it back together no matter how many parts there are.
i'm programming in Obj-c with xcode4.1, i have an array with numbers in it, and i want to visualize all of them in a label...can anyone help me around this please?
thanks!
this is the code:
combinedString=[[NSMutableArray alloc] init];
NSString *finalStringLabel=#"";
for (i=0; i<=textLength; i++) {
//character coding
char myChar = [myString characterAtIndex:i];
NSString *myCharS=[NSString stringWithFormat:#"%c", myChar];
int asciiCode=[myCharS characterAtIndex:0];
NSString *asciiS=[NSString stringWithFormat:#"%i", asciiCode];
[combinedString addObject:asciiS];
}
finalStringLabel=[NSString stringWithFormat:#"", [combinedString componentsJoinedByString:#"."]];
myLabel.text=finalStringLabel;
[combinedString release];
}
You can use this
NSArray *yourArray;
NSString *createdString = [yourArray componentsJoinedByString:#" "];
myLabel.text = createdString;
As your array is combinedString,
combinedString=[[NSMutableArray alloc] init];
looks like you are providing values after this line or this is not a property (this is a local as you are releasing it later), and your code in not complete.
Anyways,
You don't need to create an empty string and then assign new object to it, need to do as :
myLabel.text=[combinedString componentsJoinedByString:#"."];
[combinedString release];
}
I've got some trouble 'ere trying to remove the last character of an NSString.
I'm kinda newbie in Objective-C and I have no idea how to make this work.
Could you guys light me up?
NSString *newString = [oldString substringToIndex:[oldString length]-1];
Always refer to the documentation:
substringToIndex:
length
To include code relevant to your case:
NSString *str = textField.text;
NSString *truncatedString = [str substringToIndex:[str length]-1];
Try this:
s = [s substringToIndex:[s length] - 1];
NSString *string = [NSString stringWithString:#"ABCDEF"];
NSString *newString = [string substringToIndex:[string length]-1];
NSLog(#"%#",newString);
You can see = ABCDE
NSString = *string = #"abcdef";
string = [string substringToIndex:string.length-(string.length>0)];
If there is a character to delete (i.e. the length of the string is greater than 0)
(string.length>0) returns 1, thus making the code return:
string = [string substringToIndex:string.length-1];
If there is NOT a character to delete (i.e. the length of the string is NOT greater than 0)
(string.length>0) returns 0, thus making the code return:
string = [string substringToIndex:string.length-0];
which prevents crashes.
This code will just return the last character of the string and not removing it :
NSString *newString = [oldString substringToIndex:[oldString length]-1];
you may use this instead to remove the last character and retain the remaining values of a string :
str = [str substringWithRange:NSMakeRange(0,[str length] - 1)];
and also using substringToIndex to a NSString with 0 length will result to crashes.
you should add validation before doing so, like this :
if ([str length] > 0) {
str = [str substringToIndex:[s length] - 1];
}
with this, it is safe to use substring method.
NOTE : Apple will reject your application if it is vulnerable to crashes.
Simple and Best Approach
[mutableString deleteCharactersInRange:NSMakeRange([myRequestString length]-1, 1)];
Is there any way to create a new
NSString from a format string like #"xxx=%#, yyy=%#" and a NSArray of objects?
In the NSSTring class there are many methods like:
- (id)initWithFormat:(NSString *)format arguments:(va_list)argList
- (id)initWithFormat:(NSString *)format locale:(id)locale arguments:(va_list)argList
+ (id)stringWithFormat:(NSString *)format, ...
but non of them takes a NSArray as an argument, and I cannot find a way to create a va_list from a NSArray...
It is actually not hard to create a va_list from an NSArray. See Matt Gallagher's excellent article on the subject.
Here is an NSString category to do what you want:
#interface NSString (NSArrayFormatExtension)
+ (id)stringWithFormat:(NSString *)format array:(NSArray*) arguments;
#end
#implementation NSString (NSArrayFormatExtension)
+ (id)stringWithFormat:(NSString *)format array:(NSArray*) arguments
{
char *argList = (char *)malloc(sizeof(NSString *) * arguments.count);
[arguments getObjects:(id *)argList];
NSString* result = [[[NSString alloc] initWithFormat:format arguments:argList] autorelease];
free(argList);
return result;
}
#end
Then:
NSString* s = [NSString stringWithFormat:#"xxx=%#, yyy=%#" array:#[#"XXX", #"YYY"]];
NSLog( #"%#", s );
Unfortunately, for 64-bit, the va_list format has changed, so the above code no longer works. And probably should not be used anyway given it depends on the format that is clearly subject to change. Given there is no really robust way to create a va_list, a better solution is to simply limit the number of arguments to a reasonable maximum (say 10) and then call stringWithFormat with the first 10 arguments, something like this:
+ (id)stringWithFormat:(NSString *)format array:(NSArray*) arguments
{
if ( arguments.count > 10 ) {
#throw [NSException exceptionWithName:NSRangeException reason:#"Maximum of 10 arguments allowed" userInfo:#{#"collection": arguments}];
}
NSArray* a = [arguments arrayByAddingObjectsFromArray:#[#"X",#"X",#"X",#"X",#"X",#"X",#"X",#"X",#"X",#"X"]];
return [NSString stringWithFormat:format, a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9] ];
}
Based on this answer using Automatic Reference Counting (ARC): https://stackoverflow.com/a/8217755/881197
Add a category to NSString with the following method:
+ (id)stringWithFormat:(NSString *)format array:(NSArray *)arguments
{
NSRange range = NSMakeRange(0, [arguments count]);
NSMutableData *data = [NSMutableData dataWithLength:sizeof(id) * [arguments count]];
[arguments getObjects:(__unsafe_unretained id *)data.mutableBytes range:range];
NSString *result = [[NSString alloc] initWithFormat:format arguments:data.mutableBytes];
return result;
}
One solution that came to my mind is that I could create a method that works with a fixed large number of arguments like:
+ (NSString *) stringWithFormat: (NSString *) format arguments: (NSArray *) arguments {
return [NSString stringWithFormat: format ,
(arguments.count>0) ? [arguments objectAtIndex: 0]: nil,
(arguments.count>1) ? [arguments objectAtIndex: 1]: nil,
(arguments.count>2) ? [arguments objectAtIndex: 2]: nil,
...
(arguments.count>20) ? [arguments objectAtIndex: 20]: nil];
}
I could also add a check to see if the format string has more than 21 '%' characters and throw an exception in that case.
#Chuck is correct about the fact that you can't convert an NSArray into varargs. However, I don't recommend searching for the pattern %# in the string and replacing it each time. (Replacing characters in the middle of a string is generally quite inefficient, and not a good idea if you can accomplish the same thing in a different way.) Here is a more efficient way to create a string with the format you're describing:
NSArray *array = ...
NSAutoreleasePool *pool = [NSAutoreleasePool new];
NSMutableArray *newArray = [NSMutableArray arrayWithCapacity:[array count]];
for (id object in array) {
[newArray addObject:[NSString stringWithFormat:#"x=%#", [object description]]];
}
NSString *composedString = [[newArray componentsJoinedByString:#", "] retain];
[pool drain];
I included the autorelease pool for good housekeeping, since an autoreleased string will be created for each array entry, and the mutable array is autoreleased as well. You could easily make this into a method/function and return composedString without retaining it, and handle the autorelease elsewhere in the code if desired.
This answer is buggy. As noted, there is no solution to this problem that is guaranteed to work when new platforms are introduced other than using the "10 element array" method.
The answer by solidsun was working well, until I went to compile with 64-bit architecture. This caused an error:
EXC_BAD_ADDRESS type EXC_I386_GPFLT
The solution was to use a slightly different approach for passing the argument list to the method:
+ (id)stringWithFormat:(NSString *)format array:(NSArray*) arguments;
{
__unsafe_unretained id * argList = (__unsafe_unretained id *) calloc(1UL, sizeof(id) * arguments.count);
for (NSInteger i = 0; i < arguments.count; i++) {
argList[i] = arguments[i];
}
NSString* result = [[NSString alloc] initWithFormat:format, *argList] ;// arguments:(void *) argList];
free (argList);
return result;
}
This only works for arrays with a single element
There is no general way to pass an array to a function or method that uses varargs. In this particular case, however, you could fake it by using something like:
for (NSString *currentReplacement in array)
[string stringByReplacingCharactersInRange:[string rangeOfString:#"%#"]
withString:currentReplacement];
EDIT: The accepted answer claims there is a way to do this, but regardless of how fragile this answer might seem, that approach is far more fragile. It relies on implementation-defined behavior (specifically, the structure of a va_list) that is not guaranteed to remain the same. I maintain that my answer is correct and my proposed solution is less fragile since it only relies on defined features of the language and frameworks.
For those who need a Swift solution, here is an extension to do this in Swift
extension String {
static func stringWithFormat(format: String, argumentsArray: Array<AnyObject>) -> String {
let arguments = argumentsArray.map { $0 as! CVarArgType }
let result = String(format:format, arguments:arguments)
return result
}
}
Yes, it is possible. In GCC targeting Mac OS X, at least, va_list is simply a C array, so you'll make one of ids, then tell the NSArray to fill it:
NSArray *argsArray = [[NSProcessInfo processInfo] arguments];
va_list args = malloc(sizeof(id) * [argsArray count]);
NSAssert1(args != nil, #"Couldn't allocate array for %u arguments", [argsArray count]);
[argsArray getObjects:(id *)args];
//Example: NSLogv is the version of NSLog that takes a va_list instead of separate arguments.
NSString *formatSpecifier = #"\n%#";
NSString *format = [#"Arguments:" stringByAppendingString:[formatSpecifier stringByPaddingToLength:[argsArray count] * 3U withString:formatSpecifier startingAtIndex:0U]];
NSLogv(format, args);
free(args);
You shouldn't rely on this nature in code that should be portable. iPhone developers, this is one thing you should definitely test on the device.
- (NSString *)stringWithFormat:(NSString *)format andArguments:(NSArray *)arguments {
NSMutableString *result = [NSMutableString new];
NSArray *components = format ? [format componentsSeparatedByString:#"%#"] : #[#""];
NSUInteger argumentsCount = [arguments count];
NSUInteger componentsCount = [components count] - 1;
NSUInteger iterationCount = argumentsCount < componentsCount ? argumentsCount : componentsCount;
for (NSUInteger i = 0; i < iterationCount; i++) {
[result appendFormat:#"%#%#", components[i], arguments[i]];
}
[result appendString:[components lastObject]];
return iterationCount == 0 ? [result stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]] : result;
}
Tested with format and arguments:
NSString *format = #"xxx=%#, yyy=%# last component";
NSArray *arguments = #[#"XXX", #"YYY", #"ZZZ"];
Result: xxx=XXX, yyy=YYY last component
NSString *format = #"xxx=%#, yyy=%# last component";
NSArray *arguments = #[#"XXX", #"YYY"];
Result: xxx=XXX, yyy=YYY last component
NSString *format = #"xxx=%#, yyy=%# last component";
NSArray *arguments = #[#"XXX"];
Result: xxx=XXX last component
NSString *format = #"xxx=%#, yyy=%# last component";
NSArray *arguments = #[];
Result: last component
NSString *format = #"some text";
NSArray *arguments = #[#"XXX", #"YYY", #"ZZZ"];
Result: some text
I found some code on the web that claims that this is possible however I haven't managed to do it myself, however if you don't know the number of arguments in advance you also need to build the format string dynamically so I just don't see the point.
You better off just building the string by iterating the array.
You might find the stringByAppendingString: or stringByAppendingFormat: instance method handy .
One can create a category for NSString and make a function which receives a format, an array and returns the string with replaced objects.
#interface NSString (NSArrayFormat)
+ (NSString *)stringWithFormat:(NSString *)format arrayArguments:(NSArray *)arrayArguments;
#end
#implementation NSString (NSArrayFormat)
+ (NSString *)stringWithFormat:(NSString *)format arrayArguments:(NSArray *)arrayArguments {
static NSString *objectSpecifier = #"%#"; // static is redundant because compiler will optimize this string to have same address
NSMutableString *string = [[NSMutableString alloc] init]; // here we'll create the string
NSRange searchRange = NSMakeRange(0, [format length]);
NSRange rangeOfPlaceholder = NSMakeRange(NSNotFound, 0); // variables are declared here because they're needed for NSAsserts
NSUInteger index;
for (index = 0; index < [arrayArguments count]; ++index) {
rangeOfPlaceholder = [format rangeOfString:objectSpecifier options:0 range:searchRange]; // find next object specifier
if (rangeOfPlaceholder.location != NSNotFound) { // if we found one
NSRange substringRange = NSMakeRange(searchRange.location, rangeOfPlaceholder.location - searchRange.location);
NSString *formatSubstring = [format substringWithRange:substringRange];
[string appendString:formatSubstring]; // copy the format from previous specifier up to this one
NSObject *object = [arrayArguments objectAtIndex:index];
NSString *objectDescription = [object description]; // convert object into string
[string appendString:objectDescription];
searchRange.location = rangeOfPlaceholder.location + [objectSpecifier length]; // update the search range in order to minimize search
searchRange.length = [format length] - searchRange.location;
} else {
break;
}
}
if (rangeOfPlaceholder.location != NSNotFound) { // we need to check if format still specifiers
rangeOfPlaceholder = [format rangeOfString:#"%#" options:0 range:searchRange];
}
NSAssert(rangeOfPlaceholder.location == NSNotFound, #"arrayArguments doesn't have enough objects to fill specified format");
NSAssert(index == [arrayArguments count], #"Objects starting with index %lu from arrayArguments have been ignored because there aren't enough object specifiers!", index);
return string;
}
#end
Because NSArray is created at runtime we cannot provide compile-time warnings, but we can use NSAssert to tell us if number of specifiers is equal with number of objects within array.
Created a project on Github where this category can be found. Also added Chuck's version by using 'stringByReplacingCharactersInRange:' plus some tests.
Using one million objects into array, version with 'stringByReplacingCharactersInRange:' doesn't scale very well (waited about 2 minutes then closed the app). Using the version with NSMutableString, function made the string in about 4 seconds. The tests were made using simulator. Before usage, tests should be done on a real device (use a device with lowest specs).
Edit: On iPhone 5s the version with NSMutableString takes 10.471655s (one million objects); on iPhone 5 takes 21.304876s.
Here's the answer without explicitly creating an array:
NSString *formattedString = [NSString stringWithFormat:#"%# World, Nice %#", #"Hello", #"Day"];
First String is the target string to be formatted, the next string are the string to be inserted in the target.
No, you won't be able to. Variable argument calls are solved at compile time, and your NSArray has contents only at runtime.