iOS 手写签名并保存为图片

项目中用到需要手写签名并保存为图片的需求 大致思路就是利用UIBezierPath曲线将手势滑动的坐标绘制处理，然后利用CoreGraphics保存为图片

@interface CustomerSignatureView : UIView

/**
 * 获取签名图片
 */
- (UIImage *)getSignatureImage;
/**
 * 重置签名
 */
- (void)clearSignature;

@end

#import "CustomerSignatureView.h"

@interface CustomerSignatureView (){
    CGPoint points[5];
}
@property(nonatomic,assign) NSInteger control;
@property(nonatomic,strong) UIBezierPath *beizerPath;

@end
@implementation CustomerSignatureView
-(instancetype)initWithFrame:(CGRect)frame
{
    if (self == [super initWithFrame:frame]) {
        self.backgroundColor = [UIColor whiteColor];
        [self setMultipleTouchEnabled:NO];
        self.beizerPath = [UIBezierPath bezierPath];
        [self.beizerPath setLineWidth:2];
    }
    return self;
}

#pragma mark - 绘图操作
- (void)drawRect:(CGRect)rect{
    //设置签名的颜色
    UIColor *strokeColor = UIColor.blackColor;
    [strokeColor setStroke];
    
    //签名的路径绘制
    [self.beizerPath stroke];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    self.control = 0;
    UITouch *touch = [touches anyObject];
    points[0] = [touch locationInView:self];
    CGPoint startPoint = points[0];
    CGPoint endPoint = CGPointMake(startPoint.x + 1.5, startPoint.y + 2);
    [self.beizerPath moveToPoint:startPoint];
    [self.beizerPath addLineToPoint:endPoint];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
    UITouch *touch = [touches anyObject];
    CGPoint touchPoint = [touch locationInView:self];
    _control++;
    points[_control] = touchPoint;
    
    if (_control == 4){
        points[3] = CGPointMake((points[2].x + points[4].x)/2.0, (points[2].y + points[4].y)/2.0);
        
        //设置画笔起始点
        [self.beizerPath moveToPoint:points[0]];
        
        //endPoint终点 controlPoint1、controlPoint2控制点
        [self.beizerPath addCurveToPoint:points[3] controlPoint1:points[1] controlPoint2:points[2]];
        
        //setNeedsDisplay会自动调用drawRect方法，这样可以拿到UIGraphicsGetCurrentContext，就可以画画了
        [self setNeedsDisplay];
        
        points[0] = points[3];
        points[1] = points[4];
        _control = 1;
    }
}

#pragma mark - 清除签名
- (void)clearSignature{
    [self.beizerPath removeAllPoints];
    [self setNeedsDisplay];
}

#pragma mark - 获取图片
- (UIImage *)getSignatureImage {
    //设置为NO，UIView是透明这里的图片就是透明的
    UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, [UIScreen mainScreen].scale);
    [self.layer renderInContext:UIGraphicsGetCurrentContext()];
    
    UIImage *signatureImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    NSString* docDir = [NSString stringWithFormat:@"%@/Documents/Image", NSHomeDirectory()];
    [[NSFileManager defaultManager] createDirectoryAtPath:docDir withIntermediateDirectories:YES attributes:nil error:nil];
    NSString *path = [NSString stringWithFormat:@"%@/Documents/Image/IMAGE.PNG", NSHomeDirectory()];
    
    //用png是透明的
    [UIImagePNGRepresentation(signatureImage) writeToFile: path atomically:YES];
    return signatureImage;
}

@end