iOS 手写签名并生成图片

简介

由于项目需求，安卓的同事做了这样一个功能，iOS不用做，我还是找了找资料，做了一个小dome，GitHub地址，进入正题。

1.封装一个view作为签名视图，属性很好懂，就是设置签名的线的颜色，线宽，还有最后生成的图片，以及图片的缩放比例，方法分别是准备开始画线，重置以及保存

#import 

@interface CJSignatureView : UIView
// 线宽 默认1
@property (nonatomic, assign) CGFloat lineWidth;
// 线颜色 默认黑
@property (nonatomic, strong) UIColor *lineColor;
// 生成图片的缩放比例 默认1不缩放 范围0.1~1.0
@property (nonatomic, assign) CGFloat imageScale;
// 生成的图片
@property (nonatomic, strong) UIImage *signImage;

// 初始化视图之后调用 准备画图
- (void)startDraw;
// 重置
- (void)resetDraw;
// 保存成图片
- (void)saveDraw;

@end

2.初始化path

// 先声明两个全局变量
UIBezierPath *path;// 签名的线
CGPoint previousPoint;// 上一个点

#pragma mark 准备开始签名
- (void)startDraw
{
    // 背景色
    self.backgroundColor = [UIColor whiteColor];
    // 初始化 设置属性
    path = [UIBezierPath bezierPath];
    // 线宽
    path.lineWidth = _lineWidth ? _lineWidth : 1;
    // 线颜色
    if (_lineColor) {
        [_lineColor set];
    }
}

3.画线，将第一个点击的点和之后移动到的点连接

#pragma mark 画线刚开始，保存上一个点
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    // 获取点击点坐标
    UITouch * touch = touches.anyObject;
    CGPoint currentPoint = [touch locationInView:self];
    // 保存成上一点
    previousPoint = currentPoint;
    // 开始点移动到点击点
    [path moveToPoint:currentPoint];
}
#pragma mark 开始画线，连接上一个点和当前点
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    // 获取点击点坐标
    UITouch * touch = touches.anyObject;
    CGPoint currentPoint = [touch locationInView:self];
    
    // 获取两点中点
    CGPoint midPoint = midpoint(previousPoint, currentPoint);
    // 画曲线
    [path addQuadCurveToPoint:midPoint controlPoint:previousPoint];
    // 替换当前点为上一点
    previousPoint = currentPoint;
    // 画图，调用系统的darwRect:
    [self setNeedsDisplay];
}
#pragma mark 系统画线方法
- (void)drawRect:(CGRect)rect
{
    [path stroke];
}

4.写重置方法，调用startDraw重置属性，调用setNeedsDisplay重画图（path这时候时空的）

#pragma mark 重置path
- (void)resetDraw
{
    [self startDraw];
    [self setNeedsDisplay];
}

5.写保存方法，这里涉及到2个方法，截图以及缩放

#pragma mark 保存成图片
- (void)saveDraw
{
    self.signImage = [self captureWithView:self];
    if (!_imageScale) {
        return;
    }
    // 这里控制范围，范围可以自己定
    if (_imageScale < 0.1) {
        _imageScale = 0.1;
    }
    if (_imageScale > 1) {
        _imageScale = 1;
    }
    if (_imageScale != 1) {
        [self scaleImage];
    }
    
}

#pragma mark 缩放图片
- (UIImage *)scaleImage
{
    // 用这个方法 画质会变渣 
//    UIGraphicsBeginImageContext(CGSizeMake(_signImage.size.width * _imageScale, _signImage.size.height * _imageScale));
//    [_signImage drawInRect:CGRectMake(0, 0, _signImage.size.width * _imageScale, _signImage.size.height * _imageScale)];
//    self.signImage = UIGraphicsGetImageFromCurrentImageContext();
//    UIGraphicsEndImageContext();
    
    // 判断机型
    if([[UIScreen mainScreen] scale] == 2.0){      // @2x
        UIGraphicsBeginImageContextWithOptions(CGSizeMake(_signImage.size.width * _imageScale, _signImage.size.height * _imageScale), NO, 2.0);
    }else if([[UIScreen mainScreen] scale] == 3.0){ // @3x ( iPhone 6plus 、iPhone 6s plus)
        UIGraphicsBeginImageContextWithOptions(CGSizeMake(_signImage.size.width * _imageScale, _signImage.size.height * _imageScale), NO, 3.0);
    }else{
        UIGraphicsBeginImageContext(CGSizeMake(_signImage.size.width * _imageScale, _signImage.size.height * _imageScale));
    }
    // 绘制改变大小的图片
    [_signImage drawInRect:CGRectMake(0, 0, _signImage.size.width * _imageScale, _signImage.size.height * _imageScale)];
    // 从当前context中创建一个改变大小后的图片
    _signImage = UIGraphicsGetImageFromCurrentImageContext();
    // 使当前的context出堆栈
    UIGraphicsEndImageContext();
    // 返回新的改变大小后的图片
    
    return self.signImage;
}

#pragma mark 截屏
- (UIImage *)captureWithView:(UIView *)view
{
    CGRect screenRect = [view bounds];
    UIGraphicsBeginImageContext(screenRect.size);
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    [view.layer renderInContext:ctx];
    UIImage * image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

6.调用，调用比较简单了直接上代码了，这里写的例子是A控制器跳转到B控制器，在B中签名，并把图片返回到A显示

// A控制器.m代码
@implementation ViewController
{
    UIImageView *showImageView;
}
- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor cyanColor];
    
    showImageView = [[UIImageView alloc] initWithFrame:self.view.frame];
    [self.view addSubview:showImageView];
    showImageView.contentMode = UIViewContentModeScaleAspectFit;
}

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    CJDrawViewController *VC = [CJDrawViewController new];
    VC.delegate = self;
    [self presentViewController:VC animated:YES completion:nil];
}
// 代理方法
- (void)returnImage:(UIImage *)signImage
{
    showImageView.frame = CGRectMake(0, 0, signImage.size.width, signImage.size.height);
    showImageView.center = self.view.center;
    showImageView.image = signImage;
}

// B控制器.h代码
@protocol CJDrawViewControllerDelegate 
// 返回签名图片
- (void)returnImage:(UIImage *)signImage;

@end

@interface CJDrawViewController : UIViewController

@property (nonatomic, assign) id delegate;

@end

B控制器.m代码
#import "CJDrawViewController.h"
#import "CJSignatureView.h"

@interface CJDrawViewController ()

@property (nonatomic, strong) CJSignatureView *signView;

@end

@implementation CJDrawViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:self.signView];
    [self createView];
}
#pragma mark 初始化
- (CJSignatureView *)signView
{
    if (!_signView) {
        _signView = [[CJSignatureView alloc] initWithFrame:CGRectMake(0, self.view.frame.size.height/2.0-200/2.0, self.view.frame.size.width, 200)];
        _signView.lineColor = [UIColor redColor];
        _signView.lineWidth = 2;
        _signView.imageScale = 0.5;
        [_signView startDraw];
    }
    return _signView;
}
#pragma mark 创建按钮
- (void)createView
{
    NSArray *titleArr = @[@"返回", @"重置", @"保存"];
    
    CGFloat btnW = self.view.frame.size.width/3.0;
    for (int i = 0; i < titleArr.count; i++) {
        UIButton *btn = [UIButton buttonWithType:UIButtonTypeSystem];
        btn.frame = CGRectMake(btnW*i, self.view.frame.size.height-40, btnW, 40);
        [self.view addSubview:btn];
        [btn setTitle:titleArr[i] forState:UIControlStateNormal];
        [btn addTarget:self action:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];
        btn.tag = 100+i;
    }
}
#pragma mark 按钮点击方法
- (void)btnAction:(UIButton *)btn
{
    switch (btn.tag) {
        case 100:
            [self dismissViewControllerAnimated:YES completion:nil];
            break;
        case 101:
            [_signView resetDraw];
            break;
        case 102:
            [_signView saveDraw];
            if ([self.delegate respondsToSelector:@selector(returnImage:)]) {
                [self.delegate returnImage:_signView.signImage];
            }
            [self dismissViewControllerAnimated:YES completion:nil];
            break;
            
        default:
            break;
    }
}

这样，一个简单的签名就封装好了，里面有许多的东西是可以根据具体需求修改的。

结语：限于水平，本文只写了一些基本用法和注意事项，如果文中存在错误请指出，我会及时修改。