Encoding and assigning the result to a label
Here is a marginally more concise solution:

cell.titleLabel.text = [NSString stringWithCString:[[item[@"main_tag"] cStringUsingEncoding:NSISOLatin1StringEncoding] encoding:NSUTF8StringEncoding].capitalizedString;


If I had to do this more than once I would consider hiding this complexity in an NSString category like:

@interface NSString(Utils)
    -(NSString)stringWithLatinEncoding;
@end

@implementation NSString(Utils)

-(NSString)stringWithLatinEncoding
{
     return [NSString stringWithCString:[self cStringUsingEncoding:NSISOLatin1StringEncoding] encoding:NSUTF8StringEncoding];
}

@end


This will simplify your code to:

cell.titleLabel.text = ((NSString*)item[@"main_tag"]).stringWithLatinEncoding.capitalizedString;