#import

@interface TouchView : UIView
{
NSMutableArray *points;
NSArray *points_all;
CGContextRef context;
UIColor *paint_clr;
}
@property (strong,nonatomic) NSMutableArray *points;
@property (strong,nonatomic) NSArray *points_all;
@property (strong,nonatomic) UIColor *paint_clr;

@end

#import "TouchView.h"

@implementation TouchView
@synthesize points, points_all, paint_clr;

- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Initialization code
paint_clr = [UIColor greenColor];
}
return self;
}

// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
// Drawing code
if ((!self.points) || (self.points.count return;
}

context = UIGraphicsGetCurrentContext();
//设置画笔粗细
CGContextSetLineWidth(context, 5.0f);
//设置画笔颜色
//[[UIColor blueColor]set ];
// [paint_clr set];
//CGContextSetStrokeColorWithColor(context, [[UIColor blueColor]CGColor]);
CGContextSetStrokeColorWithColor(context, [paint_clr CGColor]);

//画以前的轨迹
for (int j = 0 ; j NSMutableArray *points_tmp = [points_all objectAtIndex:j];

for (int i = 0;i {
CGPoint point1 = [[points_tmp objectAtIndex:i] CGPointValue];
CGPoint point2 = [[points_tmp objectAtIndex:(i+1)] CGPointValue];
CGContextMoveToPoint(context, point1.x, point1.y);
CGContextAddLineToPoint(context, point2.x, point2.y);
CGContextStrokePath(context);
}
}

//画这次
for (int i=0; i CGPoint point1 = [[self.points objectAtIndex:i] CGPointValue];
CGPoint point2 = [[self.points objectAtIndex:(i+1)] CGPointValue];
CGContextMoveToPoint(context, point1.x, point1.y);
CGContextAddLineToPoint(context, point2.x, point2.y);
CGContextStrokePath(context);
}
}

//不支持多点触摸
- (BOOL) isMultipleTouchEnabled
{
return NO;
}

//创建一个array，并且记录初始ponit
- (void) touchesBegan:(NSSet *) touches withEvent:(UIEvent *) event
{
self.points = [NSMutableArray array];
CGPoint pt = [[touches anyObject] locationInView:self];
[self.points addObject:[NSValue valueWithCGPoint:pt]];
}

//移动过程中记录这些points
//调用setNeedsDisplay，会触发drawRect方法的调用
- (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
CGPoint pt = [[touches anyObject] locationInView:self];
[self.points addObject:[NSValue valueWithCGPoint:pt]];
[self setNeedsDisplay];
}

- (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
NSMutableArray *points_tmp = [[NSMutableArray alloc] initWithArray:self.points];
if (self.points_all == nil) {
self.points_all = [[NSArray alloc] initWithObjects:points_tmp, nil];
}else {
self.points_all = [self.points_all arrayByAddingObject:points_tmp];
}
}
@end

#import

@class TouchView;
@interface ViewController : UIViewController
{
TouchView *tv;
}
@end

#import "ViewController.h"
#import "TouchView.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.view.userInteractionEnabled = YES;

// TouchView *tv = [[TouchView alloc]initWithFrame:CGRectMake(0.0f, 0.0f, 260.0f, 260.0f)];
tv = [[TouchView alloc]initWithFrame:self.view.frame];
tv.backgroundColor = [UIColor blackColor];

[self.view addSubview:tv];

UISegmentedControl *seg = [[UISegmentedControl alloc] initWithItems:[@"White Red Blue Green Yellow" componentsSeparatedByString:@" "]];
seg.segmentedControlStyle = UISegmentedControlSegmentCenter;
seg.tintColor = [UIColor blackColor];
seg.center = CGPointMake(self.view.center.x, (self.view.bounds.size.height - seg.bounds.size.height));
[self.view addSubview:seg];

[seg addTarget:self action:@selector(colorChange:) forControlEvents:UIControlEventValueChanged];
}

- (void)viewDidUnload
{
[super viewDidUnload];
// Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

- (void) colorChange: (UISegmentedControl *) seg
{
switch ([seg selectedSegmentIndex])
{
case 0:
tv.paint_clr = [UIColor whiteColor];
break;
case 1:
tv.paint_clr = [UIColor redColor];
break;
case 2:
tv.paint_clr = [UIColor blueColor];
break;
case 3:
tv.paint_clr = [UIColor greenColor];
break;
case 4:
tv.paint_clr = [UIColor yellowColor];
break;
default:

break;
}
}

@end