在屏幕上画画（类似于手写输入键盘）

DrawInView.h

DrawInView.h 
 1 #import <UIKit/UIKit.h>
 2 
 3 @interface DrawInView : UIView
 4 
 5 @property (nonatomic, retain) NSDictionary *pointsDictionary;
 6 @property (nonatomic,assign) NSInteger beganCount;
 7 @property (nonatomic, retain) NSMutableArray *pointsArray;
 8 
 9 -(CGPoint) getCGPoint:(NSString *) key andPointIndex:(NSInteger) index;
10 -(void) clean;
11 
12 @end

DrawInView.m

DrawInView.m 
 1 #import "DrawInView.h"
 2 
 3 @implementation DrawInView
 4 
 5 @synthesize pointsDictionary;
 6 @synthesize beganCount;
 7 @synthesize pointsArray;
 8 
 9 - (id)initWithFrame:(CGRect)frame
10 {
11     self = [super initWithFrame:frame];
12     if (self) {
13         self.backgroundColor=[UIColor whiteColor];
14         
15         //添加清除按钮
16         UIButton *cleanButton=[UIButton buttonWithType:UIButtonTypeRoundedRect];
17         [cleanButton setFrame:CGRectMake(280, 25, 35, 20)];
18         [cleanButton setTitle:@"清除" forState:UIControlStateNormal];
19         [cleanButton addTarget:self action:@selector(clean) forControlEvents:UIControlEventTouchUpInside];
20         [self addSubview:cleanButton];
21     }
22     return self;
23 }
24 
25 -(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
26     if (!self.pointsDictionary) {
27         self.pointsDictionary=[NSMutableDictionary dictionary];
28         beganCount=0;
29     }
30     
31     self.pointsArray=[NSMutableArray array];
32     
33     CGPoint firstPoint=[[touches anyObject] locationInView:self];
34     NSValue *firstPointValue=[NSValue valueWithBytes:&firstPoint objCType:@encode(CGPoint)];
35     
36     [self.pointsArray addObject:firstPointValue];
37     
38     [self.pointsDictionary setValue:self.pointsArray forKey:[NSString stringWithFormat:@"%d",beganCount]];
39     
40     //累加 作为NSDictionary的Key
41     beganCount++;
42 }
43 
44 -(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
45     CGPoint point=[[touches anyObject] locationInView:self];
46     [self.pointsArray addObject:[NSValue valueWithCGPoint:point]];
47     
48     [self setNeedsDisplay];
49 }
50 
51 //系统函数
52 - (void)drawRect:(CGRect)rect
53 {
54     if (!self.pointsDictionary) return;
55     
56     //得到当前上下文
57     CGContextRef context=UIGraphicsGetCurrentContext();
58     //设置绘图颜色
59     CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor);
60     //设置画笔宽度
61     CGContextSetLineWidth(context, 4.0f);
62     
63 
64     for (int i=0; i<[self.pointsDictionary count]; i++) {
65         for (int j=0; j<[[self.pointsDictionary objectForKey:[NSString stringWithFormat:@"%d",i]] count]-1; j++) {
66             CGPoint firstPoint=[self getCGPoint:[NSString stringWithFormat:@"%d",i] andPointIndex:j];
67             CGPoint secondPoint=[self getCGPoint:[NSString stringWithFormat:@"%d",i] andPointIndex:j+1];
68             
69             //以下内容是画线
70             CGContextMoveToPoint(context, firstPoint.x, firstPoint.y);
71             CGContextAddLineToPoint(context, secondPoint.x, secondPoint.y);
72             CGContextStrokePath(context);
73         }
74 
75     }
76 }
77 
78 //通过NSDiction中的key和NSArray中index得到CGPoint变量
79 -(CGPoint) getCGPoint:(NSString *) key andPointIndex:(NSInteger) index;{
80     return [[[self.pointsDictionary objectForKey:key] objectAtIndex:index] CGPointValue];
81 }
82 
83 //点击清除按钮时触发该事件
84 -(void) clean{
85     if (self.pointsDictionary) {
86         self.pointsDictionary=nil;
87         [self setNeedsDisplay];
88     }
89 }
90 
91 -(void) dealloc{
92     [pointsDictionary release];
93     [pointsArray release];
94     
95     [super dealloc];
96 }

将上面的DrawInView（UIView的子类）添加到UIViewController子类中就可以了！

效果展示：

posted on 2012-05-04 20:00  iYiming  阅读(626)  评论(0)  编辑  收藏  举报

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