【图】分享一个iOS下实现基本绘画板功能的简单方法

代码部分
TouchView.h
代码如下：

#import UIKit/UIKit.h

@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

TouchView.m
代码如下：

#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 2)) {
        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 [self.points_all count]; j++) {
        NSMutableArray *points_tmp = [points_all objectAtIndex:j];

            for (int i = 0;i [points_tmp count]-1;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 [self.points count]-1; 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

ViewController.h
代码如下：

#import UIKit/UIKit.h

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

ViewController.m
代码如下：

#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