Split Attributed String and Retain Formatting

Question

How can you take an existing NSAttributedString and divide it based on a predefined separator while maintaining formatting? It does not seem that componentsSeparatedByString will operate on an NSAttributedString.

My current workaround produces the splits at the correct points, but only outputs an NSString. Thus losing formatting.

NSData *rtfFileData = [NSData dataWithContentsOfFile:path];
NSAttributedString *rtfFileAttributedString = [[NSAttributedString alloc] initWithData:rtfFileData options:@{NSDocumentTypeDocumentAttribute:NSRTFTextDocumentType} documentAttributes:nil error:nil];
NSString *rtfFileString = [rtfFileAttributedString string];
NSString *importSeparator = @"###";
// Wish I could do this
// NSArray *separatedArray = [rtfFileAttributedString componentsSeparatedByString:importSeparatorPref];
NSArray *separatedArray = [rtfFileString componentsSeparatedByString:importSeparatorPref];
NSLog( @"Separated array: %@", separatedArray );

Answer 1

You can make use of your split non-attributed string to split up the attributed string. One option would be:

NSData *rtfFileData = [NSData dataWithContentsOfFile:path];
NSAttributedString *rtfFileAttributedString = [[NSAttributedString alloc] initWithData:rtfFileData options:@{NSDocumentTypeDocumentAttribute:NSRTFTextDocumentType} documentAttributes:nil error:nil];
NSString *rtfFileString = [rtfFileAttributedString string];
NSString *importSeparator = @"###";
NSArray *separatedArray = [rtfFileString componentsSeparatedByString:importSeparatorPref];

NSMutableArray *separatedAttributedArray = [NSMutableArray arrayWithCapacity:separatedArray.count];
NSInteger start = 0;
for (NSString *sub in separatedArray) {
    NSRange range = NSMakeRange(start, sub.length);
    NSAttributedString *str = [rtfFileAttributedString attributedSubstringFromRange:range];
    [separatedAttributedArray addObject:str];
    start += range.length + importSeparator.length;
}

NSLog(@"Separated attributed array: ", separatedAttributedArray);

Answer 2

In Swift 4, I made the function.

func splitAttributedString(inputString: NSAttributedString, seperateBy: String) -> [NSAttributedString] {
    let input = inputString.string
    let separatedInput = input.components(separatedBy: seperateBy)
    var output = [NSAttributedString]()
    var start = 0
    for sub in separatedInput {
        let range = NSMakeRange(start, sub.utf16.count)
        let attribStr = inputString.attributedSubstring(from: range)
        output.append(attribStr)
        start += range.length + seperateBy.count
    }
    return output
}

Answer 3

In swift the answer is simple.

var string = NSAttributedString(
    string: "This string is shorter than it should be for this questions answer.",
    attributes: [.font: UIFont.systemFont(ofSize: 12)]
)
let range = NSRange(location: 0, length: 120)
let newString = string.attributedSubstring(from: range)
print(newString)

Answer 4

Here is an NSAttributedString extension that works in a similar fashion to some of the other examples here.

private extension NSAttributedString {
    func components(separatedBy separator: String) -> [NSAttributedString] {
        var result = [NSAttributedString]()
        let separatedStrings = string.components(separatedBy: separator)
        var range = NSRange(location: 0, length: 0)
        for string in separatedStrings {
            range.length = string.utf16.count
            let attributedString = attributedSubstring(from: range)
            result.append(attributedString)
            range.location += range.length + separator.utf16.count
        }
        return result
    }
}