Byte Array to NSData

Question

In a WebService JSON response is coming. In the response, there is image is coming as a byte array. I have to show the image in a UIImageView. I am trying to convert the byte array to NSData. But not getting how to do that. Any help would be appreciated. I am confident that the byte array has image data in it. Sample Byte array for your reference:

Thanks

I would recommend not to add such lengthy coding which is not needed in your question ... — IronManGill, Aug 08 '12 at 08:45
This is not JSON. Or are these squared brackets instead of parnetheses? — , Aug 08 '12 at 08:45
@H2CO3 I think that is an `NSLog()` output. And `NSLog()` prints `NSArray`s with `()` and not `[]`. — HAS, May 25 '13 at 05:53
@HAS I didn't insist this wasn't `NSLog()` output - all I wrote was "This is not JSON". And it isn't. — , May 25 '13 at 05:54

score 41 · Answer 1 · answered Aug 08 '12 at 08:50

41

Here is an example of getting your data into a NSData object.

const unsigned char bytes[] = {values here};
NSData *data = [NSData dataWithBytes:bytes length:sizeof(bytes)];
NSLog(@"%@", data);

answered Aug 08 '12 at 08:50

Paresh Navadiya

38,095
11
81
132

this answers only the very last part of the question. – Aug 08 '12 at 08:53

score 20 · Accepted Answer · 2013-08-21T10:27:59.387

20

You have to convert the JSON to an array of strings first; you can, for example, use the NSJSONSerialization class:

NSArray *strings = [NSJSONSerialization JSONObjectWithData:theJSONString options:kNilOptions error:NULL];

Then walk the strings array, convert each entry to an integer, and add it to an allocated byte pointer/array:

unsigned c = strings.count;
uint8_t *bytes = malloc(sizeof(*bytes) * c);

unsigned i;
for (i = 0; i < c; i++)
{
    NSString *str = [strings objectAtIndex:i];
    int byte = [str intValue];
    bytes[i] = byte;
}

Then finally make an NSData out of the bytes, then init an UIImage object using it:

NSData *imageData = [NSData dataWithBytesNoCopy:bytes length:c freeWhenDone:YES];
UIImage *image = [UIImage imageWithData:imageData];

edited Aug 21 '13 at 10:27

answered Aug 08 '12 at 08:50

Note that you are getting NSNumber objects not NSStrings from JSON like that. But since both respond to the intValue message your code still works. Would be better to write NSNumber or maybe even id though. – Sven May 25 '13 at 08:35
what is theJSONString? the method takes nsdata and not nsstring.. how come this works? – iosMentalist Sep 23 '14 at 14:19
How to get NSArray *strings if JSON response is not received? I get NSArray *strings nil. – Hemali Luhar Jun 20 '16 at 08:46
Setting freeWhenDone to YES caused my app to crash with malloc: *** error but stopped when I changed it to NO – rharvey Mar 07 '17 at 15:59

score 3 · Answer 3 · answered Sep 25 '14 at 03:55

and here's how to do it in Swift...

var bytes:[Byte] = [137, 80, 78, 71, 13, 10, 26, 10, 0, 0, 0, 13, 73, 72, 68, 82, 0, 0, 0, 130, 0, 0, 0, 22, 8, 6, 0, 0, 0, 12, 244, 68, 168, 0, 0, 0, 1, 115, 82, 71, 66, 0, 174, 206, 28, 233, 0, 0, 0, 4, 103, 65, 77, 65, 0, 0, 177, 143, 11, 252, 97, 5, 0, 0, 0, 9, 112, 72, 89, 115, 0, 0, 14, 196, 0, 0, 14, 196, 1, 149, 43, 14, 27, 0, 0, 3, 212, 73, 68, 65, 84, 104, 67, 237, 153, 61, 139, 20, 65, 16, 134, 55, 17, 253, 3, 114, 127, 224, 208, 204, 64, 228, 18, 3, 19, 21, 19, 35, 217, 200, 204, 15, 48, 19, 228, 48, 50, 242, 76, 12, 245, 2, 99, 47, 55, 88, 83, 65, 220, 76, 48, 57, 19, 49, 220, 95, 224, 125, 120, 34, 126, 224, 120, 207, 65, 141, 53, 189, 213, 85, 189, 238, 172, 176, 210, 5, 195, 206, 77, 87, 87, 247, 84, 189, 245, 118, 213, 220, 160, 169, 82, 61, 112, 232, 129, 65, 245, 66, 245, 0, 30, 168, 64, 168, 56, 56, 242, 64, 5, 66, 5, 66, 5, 66, 197, 192, 31, 15, 12, 142, 29, 63, 209, 228, 174, 209, 232, 101, 199, 87, 147, 201, 36, 171, 139, 141, 55, 227, 113, 179, 122, 234, 180, 171, 115, 110, 109, 173, 217, 217, 217, 53, 99, 112, 241, 210, 229, 169, 185, 216, 244, 246, 88, 50, 134, 93, 145, 18, 125, 79, 231, 230, 173, 219, 217, 253, 47, 51, 176, 92, 32, 156, 92, 89, 233, 188, 219, 189, 245, 245, 16, 8, 219, 219, 239, 27, 230, 69, 206, 76, 157, 246, 112, 99, 99, 106, 14, 78, 71, 230, 13, 94, 159, 64, 96, 47, 218, 222, 50, 7, 95, 239, 221, 5, 2, 47, 77, 96, 17, 178, 56, 10, 48, 217, 139, 192, 36, 81, 240, 158, 111, 109, 181, 251, 176, 178, 30, 102, 233, 43, 139, 75, 128, 192, 187, 161, 39, 87, 196, 108, 226, 23, 15, 8, 223, 70, 47, 154, 131, 7, 247, 155, 253, 27, 215, 155, 79, 103, 86, 59, 23, 207, 24, 67, 71, 203, 175, 253, 189, 230, 235, 179, 39, 157, 235, 199, 187, 183, 13, 23, 250, 123, 195, 171, 71, 118, 248, 229, 111, 158, 91, 130, 221, 207, 119, 239, 52, 59, 231, 207, 154, 107, 179, 6, 107, 137, 132, 64, 128, 202, 145, 167, 155, 155, 97, 112, 5, 8, 232, 91, 25, 174, 193, 129, 227, 113, 38, 0, 179, 156, 206, 49, 84, 2, 132, 89, 51, 50, 7, 208, 52, 203, 217, 151, 7, 102, 253, 174, 233, 30, 126, 126, 252, 208, 6, 44, 5, 128, 245, 55, 65, 101, 14, 66, 96, 83, 29, 43, 152, 90, 231, 251, 235, 87, 237, 22, 176, 19, 233, 235, 185, 2, 196, 16, 8, 165, 103, 191, 232, 105, 167, 64, 237, 158, 51, 1, 217, 181, 225, 112, 74, 7, 16, 105, 241, 108, 244, 5, 4, 246, 66, 112, 229, 138, 128, 239, 49, 130, 100, 109, 9, 8, 68, 103, 247, 202, 133, 44, 16, 34, 59, 4, 94, 196, 2, 1, 207, 96, 32, 139, 153, 176, 13, 248, 90, 32, 224, 136, 156, 195, 117, 198, 122, 122, 105, 150, 144, 85, 158, 190, 181, 158, 117, 254, 70, 199, 140, 55, 158, 218, 155, 199, 150, 204, 245, 106, 4, 178, 211, 10, 28, 52, 205, 24, 23, 247, 150, 14, 99, 22, 35, 136, 46, 129, 204, 101, 59, 64, 128, 238, 83, 187, 28, 31, 233, 209, 147, 234, 0, 220, 22, 8, 81, 6, 136, 19, 60, 61, 139, 46, 75, 106, 11, 177, 205, 113, 97, 117, 20, 243, 4, 175, 111, 32, 68, 93, 131, 21, 12, 28, 157, 138, 197, 26, 204, 205, 29, 13, 114, 116, 96, 199, 2, 3, 243, 172, 140, 103, 29, 97, 3, 126, 249, 219, 154, 223, 2, 129, 5, 162, 2, 73, 186, 136, 92, 96, 114, 231, 38, 52, 90, 18, 204, 180, 93, 45, 169, 17, 116, 129, 103, 221, 75, 231, 81, 98, 43, 98, 22, 93, 183, 228, 142, 36, 11, 8, 60, 75, 37, 167, 103, 1, 1, 6, 209, 98, 129, 136, 121, 127, 115, 36, 9, 59, 116, 128, 16, 177, 130, 156, 221, 179, 2, 129, 151, 136, 90, 79, 198, 115, 242, 47, 106, 4, 214, 240, 186, 34, 41, 110, 163, 154, 164, 132, 158, 177, 1, 101, 167, 20, 157, 99, 132, 20, 72, 86, 230, 151, 50, 130, 102, 7, 125, 223, 1, 66, 196, 10, 146, 17, 139, 0, 66, 238, 35, 19, 123, 138, 170, 119, 93, 228, 165, 247, 227, 195, 2, 80, 23, 118, 158, 173, 40, 17, 116, 75, 59, 11, 35, 16, 112, 221, 38, 114, 111, 213, 8, 60, 183, 24, 161, 20, 8, 95, 30, 63, 10, 107, 4, 169, 37, 210, 22, 117, 10, 8, 57, 103, 80, 221, 71, 244, 234, 181, 84, 81, 59, 233, 101, 90, 201, 177, 18, 209, 122, 180, 119, 230, 35, 81, 167, 83, 242, 49, 105, 150, 246, 77, 3, 130, 190, 126, 30, 32, 48, 223, 90, 155, 35, 3, 144, 88, 44, 196, 250, 204, 153, 2, 2, 206, 176, 40, 178, 36, 171, 254, 7, 32, 148, 116, 58, 105, 123, 155, 130, 56, 151, 241, 94, 27, 40, 140, 49, 15, 16, 216, 199, 172, 107, 3, 2, 10, 209, 129, 20, 88, 250, 101, 96, 5, 93, 120, 105, 54, 64, 79, 198, 104, 13, 245, 189, 215, 91, 243, 37, 49, 87, 216, 201, 71, 171, 28, 43, 48, 47, 93, 43, 183, 7, 235, 185, 174, 63, 188, 226, 82, 214, 231, 61, 162, 34, 52, 250, 178, 136, 115, 115, 25, 168, 1, 129, 142, 238, 8, 184, 151, 234, 94, 126, 211, 175, 143, 100, 183, 238, 6, 244, 7, 41, 222, 1, 102, 64, 199, 99, 38, 198, 244, 145, 83, 255, 13, 29, 85, 127, 61, 140, 19, 92, 249, 76, 44, 191, 58, 248, 61, 44, 225, 154, 72, 215, 182, 148, 43, 16, 22, 29, 133, 37, 177, 95, 129, 176, 36, 129, 90, 244, 54, 43, 16, 22, 237, 225, 37, 177, 255, 27, 38, 183, 224, 140, 178, 26, 189, 95, 0, 0, 0, 0, 73, 69, 78, 68, 174, 66, 96, 130];

var imageData:NSData = NSData(bytes: bytes, length: bytes.count);
var image:UIImage = UIImage(data: imageData);
var imageView:UIImageView = UIImageView(image: image);

score 2 · Answer 4 · answered Nov 30 '14 at 19:58

I have my way to do it in Swift

if let serverBytesArray = serverAnswer as? NSArray {
    var bytes:[Byte] = []
    for serverByte in serverBytesArray {
        bytes.append(Byte(serverByte as UInt))
    }
    var data = NSData(bytes: bytes, length: bytes.count);
    let tmpDir = NSTemporaryDirectory()
    data.writeToFile(tmpDir.stringByAppendingPathComponent("test.pdf"), atomically: true)
}

Byte Array to NSData

4 Answers4

Linked