Its much useful for drawing something on screen by touch.
1) Declare 4 objects in .h file
CGPoint lastPoint;
BOOL mouseSwiped;
int mouseMoved;
UIImageView *signImage;
2) First create a UIImageView object ie. a blank image in viewDidLoad
signImage = [[UIImageView alloc ] initWithFrame:CGRectMake(15, 60, 290, 320)];
signImage.image = nil;
signImage.tag = 1000;
signImage.layer.borderWidth = 3.0;
signImage.layer.borderColor = [[UIColor lightGrayColor] CGColor];
[self.view addSubview:signImage];
2) Then add 3 methods TouchesBegin, TouchesMoved & TouchesEnd
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
mouseSwiped = NO;
UITouch *touch = [touches anyObject];
CGPoint touchLocation = [touch locationInView:self.view];
if (CGRectContainsPoint(signImage.frame, touchLocation))
{
lastPoint = [touch locationInView:signImage];
}
NSLog(@”Last :%.2f – %.2f”,lastPoint.x, lastPoint.y);
}
– (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
mouseSwiped = YES;
CGPoint currentPoint;
UITouch *touch = [touches anyObject];
CGPoint touchLocation = [touch locationInView:self.view];
if (CGRectContainsPoint(signImage.frame, touchLocation))
{
currentPoint = [touch locationInView:signImage];
UIGraphicsBeginImageContext(signImage.frame.size);
[first_signImage.image drawInRect:CGRectMake(0, 0, signImage.frame.size.width, signImage.frame.size.height)];CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
signImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
//currentPoint.y -= 150;
lastPoint = currentPoint;
mouseMoved++;
if (mouseMoved == 10) {
mouseMoved = 0;
}
}
– (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
if(!mouseSwiped) {
CGPoint currentPoint;
UITouch *touch = [touches anyObject];
CGPoint touchLocation = [touch locationInView:self.view];
if (CGRectContainsPoint(signImage.frame, touchLocation))
{
currentPoint = [touch locationInView:signImage];
UIGraphicsBeginImageContext(signImage.frame.size);
[signImage.image drawInRect:CGRectMake(0, 0, signImage.frame.size.width, signImage.frame.size.height)];CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
signImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
}
}
