擦除石英2D中的操作

Question

有关如何在Quartz 2D中执行擦除操作的任何建议吗？

Answer 1

CGContextClearRect(UIGraphicsGetCurrentContext(), rect);

Answer 2

   if (clear) {

        CGContextSetBlendMode(UIGraphicsGetCurrentContext(),kCGBlendModeNormal);
        CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(), [UIColor              colorWithPatternImage:[UIImage imageNamed:@"rainbow-colors-orange-320x480.jpg"]].CGColor);
       // your background image. make sure it is same size

   } else {
        CGContextSetBlendMode(UIGraphicsGetCurrentContext(),kCGBlendModeNormal);
        NSUInteger red, green, blue;
        sscanf([stringColor UTF8String], "#%02X%02X%02X", &red, &green, &blue);
        UIColor *colors = [UIColor colorWithRed:red/255.0 green:green/255.0 blue:blue/255.0 alpha:1];
        CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(), [colors CGColor]);

   }