How to convert NSString to NSArray with characters one by one in Objective-C [duplicate]

Question

I'd like to convert NSString(ex. @"HELLO") to NSArray(ex. [@"H", @"E", @"L", @"L", @"O", nil]).

First, I tried to use componentsSeparatedByString. But it needs to indicate separator, so I could not. How can I do that?

Answer 1

The proper way to split a string into an array is to do the following (as an NSString category method):

@interface NSString (ConvertToArray)
-(NSArray *)convertToArray;
@end

@implementation NSString (ConvertToArray)

- (NSArray *)convertToArray {
    NSMutableArray *arr = [[NSMutableArray alloc] init];
    NSUInteger i = 0;
    while (i < self.length) {
        NSRange range = [self rangeOfComposedCharacterSequenceAtIndex:i];
        NSString *chStr = [self substringWithRange:range];
        [arr addObject:chStr];
        i += range.length;
    }

    return arr;
}

@end

NSArray *array = [@"Hello 😄" convertToArray];
NSLog(@"array = %@", array);

Solutions that hardcode a range length of 1 will fail if the string contains Unicode characters of \U10000 or later. This include Emoji characters as well as many others.

Answer 2

Here is my code:

@interface NSString (ConvertToArray)
-(NSArray *)convertToArray;
@end

@implementation NSString (ConvertToArray)

-(NSArray *)convertToArray
{
    NSMutableArray *arr = [[NSMutableArray alloc]init];
    for (int i=0; i < self.length; i++) {
        NSString *tmp_str = [self substringWithRange:NSMakeRange(i, 1)];
        [arr addObject:[tmp_str stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
    }
    return arr;
}
@end

:

- (void)foo
{
    NSString *exString = @"HELLO";
    NSArray *arr = [exString convertToArray];
    for (NSString *str  in arr) {
        NSLog(@"%@\n",str);
    }
}