Draw a 5 pixel line on UIView [duplicate] - ios

Question

This question already has answers here:
What's the best approach to draw lines between views?
(2 answers)
Closed 9 years ago.
I have a very simple (well hopefully very simple) question. In Objective-C, how do you draw a line between two points and add it to a UIView? I have tried using a UIImageView and manipulating its Transform property, but that ends up turning the line into a square or a rectangle when using the following code:
[[self tline] setFrame:CGRectMake(start.x, start.y, width, 5)];
[[self tline] setTransform:CGAffineTransformMakeRotation(angle)];
I have two CGPoints, start and end, and I would like to draw a dynamic 5px line between the two points and add it to my subview.
BK:
The point start is the point where the user begins touching the screen, and the point end is the point where the user's finger is currently. Obviously this will move a lot during gameplay. I need to be able to move this line to connect these two points.
I am using the touchesBegan:, Moved:, and Ended: methods to create, move, and destroy the line.
CoreGraphics
I have the following code; how do I add this line to self.view?
CGContextRef c = UIGraphicsGetCurrentContext();
CGFloat color[4] = {1.0f, 1.0f, 1.0f, 0.6f};
CGContextSetStrokeColor(c, color);
CGContextBeginPath(c);
CGContextMoveToPoint(c, start.x, start.y);
CGContextAddLineToPoint(c, end.x, end.y);
CGContextSetLineWidth(c, 5);
CGContextSetLineCap(c, kCGLineCapRound);
CGContextStrokePath(c);
Custom UIView:
#import <UIKit/UIKit.h>
#interface DrawingView : UIView
#property (nonatomic) CGPoint start;
#property (nonatomic) CGPoint end;
- (void)drawRect:(CGRect)rect;
#end
#import "DrawingView.h"
#implementation DrawingView
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
}
return self;
}
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
CGContextSetLineCap(context, kCGLineCapSquare);
CGContextSetStrokeColorWithColor(context, [UIColor whiteColor].CGColor); //change color here
CGFloat lineWidth = 5.0; //change line width here
CGContextSetLineWidth(context, lineWidth);
CGPoint startPoint = [self start];
CGPoint endPoint = [self end];
CGContextMoveToPoint(context, startPoint.x + lineWidth/2, startPoint.y + lineWidth/2);
CGContextAddLineToPoint(context, endPoint.x + lineWidth/2, endPoint.y + lineWidth/2);
CGContextStrokePath(context);
CGContextRestoreGState(context);
NSLog(#"%f",_end.x);
}
- (void)setEnd:(CGPoint)end
{
_end = end;
[self setNeedsDisplay];
}
#end
drawRect: is only called when I initialize the view...
Draw method in UIViewController:
- (void)drawTLine:(CGPoint)start withEndPoint:(CGPoint)end
{
[[self dview] setStart:start];
[[self dview] setEnd:end];
[[self dview] drawRect:[self dview].frame];
}
This is how I add the drawing view:
DrawingView* dview = [[DrawingView alloc] initWithFrame:self.view.frame];
[dview setBackgroundColor:[UIColor clearColor]];
[self.view addSubview:dview];

Answer 1

Subclass UIView and perform custom drawing using the drawRect: method
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
CGContextSetLineCap(context, kCGLineCapSquare);
CGContextSetStrokeColorWithColor(context, [UIColor blackColor].CGColor); //change color here
CGFloat lineWidth = 1.0; //change line width here
CGContextSetLineWidth(context, lineWidth);
CGPoint startPoint = rect.origin; //change start point here
CGPoint endPoint = {.x = CGRectGetMaxX(rect), .y = startPoint.y} //change end point here
CGContextMoveToPoint(context, startPoint.x + lineWidth/2, startPoint.y + lineWidth/2);
CGContextAddLineToPoint(context, endPoint.x + lineWidth/2, endPoint.y + lineWidth/2);
CGContextStrokePath(context);
CGContextRestoreGState(context);
}
This will draw a black 1px line at the top of your UIView.
If you need to update the line you can just use some properties like
#property (nonatomic) CGPoint startPoint;
and provide a custom implementation for the setter like
- (void)setStartPoint:(CGPoint)point {
_point = point;
[self setNeedsDisplay]; // this will cause drawRect: to be called again
}
Do that for every property that you wish to control and make your drawRect: use such properties for drawing.

Answer 2

you can create and UIBezierPath like this
UIBezierPath path = [[UIBezierPath alloc] init]
[path moveToPoint: CGPoint(x,y)] // X and Y, start point
[path addLineToPoint:CGPoint(x2,y2) // X2 and Y2, end point
if you want to create a shape you can put more points with addLineToPoint: method and finish use
closePath method
I hope help you