UIView上签名绘图示例

ipad上绘图的软件不错吧，以有有一个小朋友写了一个涂鸦软件，大买呀。这儿有一个示例。

Canvas2D.h

#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>


@interface Canvas2D : UIView {
    NSMutableArray* arrayStrokes;
	UIColor *currentColor;
	
}

@property (retain) NSMutableArray* arrayStrokes;

@end

Canvas2D.m

#import "Canvas2D.h"


@implementation Canvas2D

@synthesize arrayStrokes;

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
		self.arrayStrokes = [NSMutableArray array];
    }
    return self;
}

- (id)initWithCoder:(NSCoder *)aDecoder {
    if ((self = [super initWithCoder:aDecoder])) {
		self.arrayStrokes = [NSMutableArray array];
    }
	
    return self;
}


// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // Drawing code
	CGContextRef context = UIGraphicsGetCurrentContext();
	
	CGContextSetLineWidth(context, 2.0);
	
	CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
	
	CGFloat components[] = {0.0, 0.0, 1.0, 1.0};
	CGColorRef color = CGColorCreate(colorspace, components);
	
	CGContextSetStrokeColorWithColor(context, color);
	
	CGContextMoveToPoint(context, 0, 0);
	CGContextAddLineToPoint(context, 300, 400);
	
	CGContextStrokePath(context);
	CGColorSpaceRelease(colorspace);
	CGColorRelease(color);
	
	if (self.arrayStrokes)
	{
		int arraynum = 0;
		// each iteration draw a stroke
		// line segments within a single stroke (path) has the same color and line width
		for (NSDictionary *dictStroke in self.arrayStrokes)
		{
			NSArray *arrayPointsInstroke = [dictStroke objectForKey:@"points"];
			UIColor *color = [dictStroke objectForKey:@"color"];
			float size = [[dictStroke objectForKey:@"size"] floatValue];
			[color set];		// equivalent to both setFill and setStroke
			
			// draw the stroke, line by line, with rounded joints
			UIBezierPath* pathLines = [UIBezierPath bezierPath];
			CGPoint pointStart = CGPointFromString([arrayPointsInstroke objectAtIndex:0]);
			[pathLines moveToPoint:pointStart];
			for (int i = 0; i < (arrayPointsInstroke.count - 1); i++)
			{
				CGPoint pointNext = CGPointFromString([arrayPointsInstroke objectAtIndex:i+1]);
				[pathLines addLineToPoint:pointNext];
			}
			pathLines.lineWidth = size;
			pathLines.lineJoinStyle = kCGLineJoinRound;
			pathLines.lineCapStyle = kCGLineCapRound;
			[pathLines stroke];
			
			arraynum++;
		}
	}

}

// Start new dictionary for each touch, with points and color
- (void) touchesBegan:(NSSet *) touches withEvent:(UIEvent *) event
{
	NSMutableArray *arrayPointsInStroke = [NSMutableArray array];
	NSMutableDictionary *dictStroke = [NSMutableDictionary dictionary];
	[dictStroke setObject:arrayPointsInStroke forKey:@"points"];
	[dictStroke setObject:[UIColor blackColor] forKey:@"color"];
	[dictStroke setObject:[NSNumber numberWithFloat:5] forKey:@"size"];
	
	CGPoint point = [[touches anyObject] locationInView:self];
	[arrayPointsInStroke addObject:NSStringFromCGPoint(point)];
	
	[self.arrayStrokes addObject:dictStroke];
}

// Add each point to points array
- (void) touchesMoved:(NSSet *) touches withEvent:(UIEvent *) event
{
	CGPoint point = [[touches anyObject] locationInView:self];
	CGPoint prevPoint = [[touches anyObject] previousLocationInView:self];
	NSMutableArray *arrayPointsInStroke = [[self.arrayStrokes lastObject] objectForKey:@"points"];
	[arrayPointsInStroke addObject:NSStringFromCGPoint(point)];
	
	CGRect rectToRedraw = CGRectMake(\
									 ((prevPoint.x>point.x)?point.x:prevPoint.x)-5,\
									 ((prevPoint.y>point.y)?point.y:prevPoint.y)-5,\
									 fabs(point.x-prevPoint.x)+2*5,\
									 fabs(point.y-prevPoint.y)+2*5\
									 );
	[self setNeedsDisplayInRect:rectToRedraw];
}

// Send over new trace when the touch ends
- (void) touchesEnded:(NSSet *) touches withEvent:(UIEvent *) event
{
}



- (void)dealloc
{
	[arrayStrokes release];
    [super dealloc];
}

@end

记得加入QuartzCore.framework

用法: 在xib中的view关联Canvas2D