Objective-C Requires Chilkat v11.7.0+

QR Code Colors and Transparent Background

See more QR Code Examples

Demonstrates colored QR codes. render.foreground is the color of the dark modules and render.background the color behind them, each as #RRGGBB. Either can instead be an object with a color and an opacity from 0 to 1, and a background opacity of 0 gives a PNG with a transparent background to place over a page or a design. Readers need contrast: keep the modules clearly darker than whatever ends up behind them. Objective-C

#import <CkoFormats.h>
#import <CkoJsonObject.h>

BOOL success = NO;

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

CkoFormats *fmt = [[CkoFormats alloc] init];
CkoJsonObject *jsonOut = [[CkoJsonObject alloc] init];

//  Dark blue modules on a pale yellow background.
CkoJsonObject *json = [[CkoJsonObject alloc] init];
[json UpdateString: @"payload.text" value: @"https://www.chilkatsoft.com/"];
[json UpdateInt: @"render.moduleSize" value: [NSNumber numberWithInt: 6]];
[json UpdateString: @"render.foreground" value: @"#1B3A6B"];
[json UpdateString: @"render.background" value: @"#FFF8DC"];
[json UpdateString: @"output.path" value: @"qa_output/qr_blue.png"];
[json UpdateBool: @"output.overwrite" value: YES];
[json UpdateString: @"output.return" value: @"none"];
success = [fmt QrCode: @"generate" jsonIn: json jsonOut: jsonOut];
if (success == NO) {
    NSLog(@"%@",fmt.LastErrorText);
    return;
}

NSLog(@"%@%@%@%d%@",@"colored: ",[jsonOut StringOf: @"outputs[0].path"],@", ",[[jsonOut IntOf: @"outputs[0].byteCount"] intValue],@" bytes");

//  The image written to qa_output/qr_blue.png:

//  

//  The same modules on a fully transparent background.
CkoJsonObject *json2 = [[CkoJsonObject alloc] init];
[json2 UpdateString: @"payload.text" value: @"https://www.chilkatsoft.com/"];
[json2 UpdateInt: @"render.moduleSize" value: [NSNumber numberWithInt: 6]];
[json2 UpdateString: @"render.foreground" value: @"#1B3A6B"];
[json2 UpdateString: @"render.background.color" value: @"#FFFFFF"];
[json2 UpdateNumber: @"render.background.opacity" numericStr: @"0"];
[json2 UpdateString: @"output.path" value: @"qa_output/qr_transparent.png"];
[json2 UpdateBool: @"output.overwrite" value: YES];
[json2 UpdateString: @"output.return" value: @"none"];
success = [fmt QrCode: @"generate" jsonIn: json2 jsonOut: jsonOut];
if (success == NO) {
    NSLog(@"%@",fmt.LastErrorText);
    return;
}

NSLog(@"%@%@%@%d%@",@"transparent: ",[jsonOut StringOf: @"outputs[0].path"],@", ",[[jsonOut IntOf: @"outputs[0].byteCount"] intValue],@" bytes");

//  qa_output/qr_transparent.png, placed here over a checkerboard and over a colored page
//  to show that whatever is behind the image shows through:

//  

//  Sample output:

//  colored: qa_output/qr_blue.png, 1345 bytes
//  transparent: qa_output/qr_transparent.png, 1377 bytes