如何在ios中进行自定义绘图？

Question

I want to make custom drawing so that i could convert it to image.

i have heard of UIBezierPath but donot know much about it, my purpose is to change color of it on basis of user's selection of color.

Answer 1

Create a CGGraphcisContext and get an image like this:

UIGraphicsBeginImageContextWithOptions(bounds.size, NO , [[UIScreen mainScreen] scale]);

// set the fill color (UIColor *)
[userSelectedColor setFill];

//create your path
UIBezierPath *path = ...

//fill the path with your color
[path fill]; 

UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

You might have to combine multiple paths to get your desired shape. First create the 'drop' with bezier paths. The path might look something like this:

//Create the top half of the circle
UIBezierPath *drop = [UIBezierPath bezierPathWithArcCenter:CGPointMake(CGRectGetWidth(bounds)*0.5f, CGRectGetWidth(bounds)*0.5f)
                       radius:CGRectGetWidth(bounds)*0.5f
                       startAngle:0
                       endAngle:DEGREES_TO_RADIANS(180)
                       clockwise:NO];

//Add the first half of the bottom part
[drop addCurveToPoint:CGPointMake(CGRectGetWidth(bounds)*0.5f,CGRectGetHeight(bounds)) 
        controlPoint1:CGPointMake(CGRectGetWidth(bounds),CGRectGetWidth(bounds)*0.5f+CGRectGetHeight(bounds)*0.1f)]
        controlPoint2:CGPointMake(CGRectGetWidth(bounds)*0.6f,CGRectGetHeight(bounds)*0.8f)];

//Add the second half of the bottom part beginning from the sharp corner
[drop addCurveToPoint:CGPointMake(0,CGRectGetWidth(bounds)*0.5f) 
        controlPoint1:CGPointMake(CGRectGetWidth(bounds)*0.4f,CGRectGetHeight(bounds)*0.8f)
       controlPoint2:CGPointMake(0,CGRectGetWidth(bounds)*0.5f+CGRectGetHeight(bounds)*0.1f)];

[drop closePath];

Not entirely sure if this works since I couldn't test it right now. You might have to play with the controls points a bit. It could be that I made some error with the orientation.