iOS - 手写签名(透明背景)

1.引入【#import "BJTSignView.h"】

代码如下：

#import <UIKit/UIKit.h>

@interface BJTSignView : UIView
/**
 * 获取签名图片
 */
- (UIImage *)getSignatureImage;
/**
 * 清除签名
 */
- (void)clearSignature;
@end

#import "BJTSignView.h"
@interface BJTSignView (){
    CGPoint points[5];
}
@property(nonatomic,assign) NSInteger control;
@property(nonatomic,strong) UIBezierPath *beizerPath;
@end

@implementation BJTSignView

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.backgroundColor = [UIColor clearColor];
        [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 redColor];
    [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

2.实现方法：

定义属性：

@property(nonatomic,strong) BJTSignView *signView;
@property(nonatomic,strong) UIImageView *imageView;

实现代码：

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.view.backgroundColor = [UIColor whiteColor];
    //画布
    UIView *backView = [[UIView alloc] initWithFrame:CGRectMake(0, 50, kScreenWidth, 200)];
    backView.layer.borderWidth = 2;
    backView.layer.borderColor = [[UIColor redColor] CGColor];
    [self.view addSubview:backView];
    self.signView = [[BJTSignView alloc] initWithFrame:backView.bounds];
    [backView addSubview:self.signView];
    
    
    UIButton *clearBtn = [[UIButton alloc] initWithFrame:CGRectMake(0, 260, kScreenWidth, 30)];
    [clearBtn setTitle:@"清除签名" forState:UIControlStateNormal];
    [clearBtn setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    [self.view addSubview:clearBtn];
    [clearBtn addTarget:self action:@selector(clearBtnClick) forControlEvents:UIControlEventTouchUpInside];
    
    UIButton *imageBtn = [[UIButton alloc] initWithFrame:CGRectMake(0, 300, kScreenWidth, 30)];
    [imageBtn setTitle:@"生成图片" forState:UIControlStateNormal];
    [imageBtn setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    [self.view addSubview:imageBtn];
    [imageBtn addTarget:self action:@selector(imageBtnClick) forControlEvents:UIControlEventTouchUpInside];
    
    self.imageView = [[UIImageView alloc] initWithFrame:CGRectMake((kScreenWidth - kScreenWidth/2)/2,380 , kScreenWidth/2, 200/2)];
    self.imageView.backgroundColor = [UIColor blackColor];
    [self.view addSubview:self.imageView];
    
}
#pragma mark - 清楚图片
- (void)clearBtnClick{
    [self.signView clearSignature];
}

#pragma mark - 生成图片
- (void)imageBtnClick{
    UIImage *image  =  [self.signView getSignatureImage];
    self.imageView.image = image;
}