CGContext Reference

Draw line

CGContextRef context = UIGraphicsGetCurrentContext();

CGContextSetLineWidth(context, 5.0);
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGContextMoveToPoint(context, 200, 400);
CGContextAddLineToPoint(context, 100, 100);
CGContextStrokePath(context);
CGColorSpaceRelease(colorspace);

Draw Text

Draw To requires Core Text framework to be added in the Build Phase

[NSString* textToDraw = @"Welcome to the world Of IOS";

    CFStringRef stringRef = (__bridge CFStringRef)textToDraw;

    CFAttributedStringRef currentText = CFAttributedStringCreate(NULL, stringRef, NULL);
    CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(currentText);
    CGRect frameRect = CGRectMake(0, 0, 300, 100);
    CGMutablePathRef framePath = CGPathCreateMutable();
    CGPathAddRect(framePath, NULL, frameRect);

    CFRange currentRange = CFRangeMake(0, 0);
    CTFrameRef frameRef = CTFramesetterCreateFrame(framesetter, currentRange, framePath, NULL);
    CGPathRelease(framePath);
    CGContextRef currentContext = UIGraphicsGetCurrentContext();

    CGContextSetTextMatrix(currentContext, CGAffineTransformIdentity);
    CGContextTranslateCTM(currentContext, 200, 300);
    CGContextScaleCTM(currentContext, 2, -2);
    CTFrameDraw(frameRef, currentContext);

    CFRelease(frameRef);
    CFRelease(stringRef);
    CFRelease(framesetter);

Remarks

The CGContextRef opaque type represents a Quartz 2D drawing destination. A graphics context contains drawing parameters and all device-specific information needed to render the paint on a page to the destination, whether the destination is a window in an application, a bitmap image, a PDF document, or a printer.