ios -[NSArray componentsJoinedByString] with condition - ios

Question

I want to use -[NSArray componentsJoinedByString] with some condition for example : concatenate all elements of my array with ", " except the last one where I want an " and ".
It python it would be something like :
', '.join(array[:-1]) + ' and ' + array[-1]
Is there a way or a method that would do the trick in one line, avoiding all the if else stuff ?

Answer 1

You can use subarrayWithRange: and stringWithFormat: to do the same thing. You do need at least 1 if to check the count of items in the array and ensure that you don't have an index exception.

Answer 2

try like this,i dont know is this effiecient or not but check once,
NSArray *arr= [[NSArray alloc]initWithObjects:#"1",#"2",#"3", nil];
NSString *string = [arr componentsJoinedByString:#","];
NSString *str= [NSString stringWithFormat:#"%# and %#",[string substringToIndex:[string length]-[[arr lastObject] length]-1],[arr lastObject]];
NSLog(#"%#",str);

Answer 3

It might not be the most efficient, but it is a nice simple solution to take an array of objects that have string representations and turn them into a comma separated list such as 1, 2, 3, and 4.
#implementation NSArray (MyCollection)
- (NSString *)stringCommaAndSeparated
{
return [self stringCommaAndSeparatedUsingStringConverter:^NSString *(id object) {
assert( [object isKindOfClass:NSString.class] );
return (NSString *)object;
}];
}
- (NSString *)stringCommaAndSeparatedUsingStringConverter:(NSString *(^)(id object))stringConverter
{
assert( stringConverter );
if( self.count == 0 )
return #"";
if( self.count == 1 )
return stringConverter(self.firstObject);
if( self.count == 2 )
return [NSString stringWithFormat:NSLocalizedString(#"%# and %#", nil), stringConverter(self[0]), stringConverter(self[1]) ];
NSMutableString *string = [[NSMutableString alloc] init];
for( int index = 0; index < self.count-1; index += 1 )
[string appendFormat:NSLocalizedString(#"%#, ", nil), stringConverter(self[index])];
[string appendFormat:NSLocalizedString(#"and %#", nil), stringConverter(self.lastObject)];
return string; // This is returning a mutable string, but we could copy it to an immutable one!
}
#end
Here is an example of this in action:
// Results in #"1, 2, 3, and 4"
NSString *str = [#[#"1", #"2", #"3", #"4"] stringCommaAndSeparated];
// Results in #"1, 2, 3, and 4"
NSString *str2 = [#[#(1), #(2), #(3), #(4)] stringCommaAndSeparatedUsingStringConverter:^NSString *(id object) {
assert( [object isKindOfClass:NSNumber.class] );
NSNumber *number = object;
return number.stringValue;
}];

Answer 4

Here's my category solution, based on Wain's answer:
#implementation NSArray (NSString)
- (NSString *)listStringUsingLocale:(NSLocale *)locale
{
if(!self.count)
return nil;
if(!locale)
locale = [NSLocale currentLocale];
NSString *language = [locale objectForKey: NSLocaleLanguageCode];
if([language isEqualToString:#"en"])
{
if (self.count > 1)
{
NSArray *arr1 = [self subarrayWithRange:NSMakeRange(0, self.count - 1)];
return [NSString stringWithFormat:#"%# and %#", [arr1 componentsJoinedByString:#", "], self.lastObject];
}
else
{
return self[0];
}
}
return nil;
}
#end
I've added the option to add locale-based options.