触摸事件练习 -- 画画板（截屏分类）

Main.storyboard

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="5053" systemVersion="13D65" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" initialViewController="vXZ-lx-hvc">
    <dependencies>
        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="3733"/>
    </dependencies>
    <scenes>
        <!--View Controller-->
        <scene sceneID="ufC-wZ-h7g">
            <objects>
                <viewController id="vXZ-lx-hvc" customClass="LWTViewController" sceneMemberID="viewController">
                    <layoutGuides>
                        <viewControllerLayoutGuide type="top" id="jyV-Pf-zRb"/>
                        <viewControllerLayoutGuide type="bottom" id="2fi-mo-0CV"/>
                    </layoutGuides>
                    <view key="view" contentMode="scaleToFill" id="kh9-bI-dsS">
                        <rect key="frame" x="0.0" y="0.0" width="320" height="480"/>
                        <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                        <subviews>
                            <view contentMode="scaleToFill" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="O12-F5-sTX" customClass="LWTView">
                                <rect key="frame" x="0.0" y="80" width="320" height="320"/>
                                <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="calibratedWhite"/>
                            </view>
                            <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="Uig-1j-G4F">
                                <rect key="frame" x="20" y="20" width="46" height="30"/>
                                <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                                <state key="normal" title="清屏">
                                    <color key="titleColor" red="0.30005167820127365" green="0.0" blue="1" alpha="1" colorSpace="calibratedRGB"/>
                                    <color key="titleShadowColor" white="0.5" alpha="1" colorSpace="calibratedWhite"/>
                                </state>
                                <connections>
                                    <action selector="clearOnClick" destination="vXZ-lx-hvc" eventType="touchUpInside" id="Pi3-JJ-h4m"/>
                                </connections>
                            </button>
                            <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="qxJ-JE-L8i">
                                <rect key="frame" x="254" y="20" width="46" height="30"/>
                                <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                                <state key="normal" title="保存">
                                    <color key="titleColor" red="0.3000516782" green="0.0" blue="1" alpha="1" colorSpace="calibratedRGB"/>
                                    <color key="titleShadowColor" white="0.5" alpha="1" colorSpace="calibratedWhite"/>
                                </state>
                                <connections>
                                    <action selector="saveOnClick" destination="vXZ-lx-hvc" eventType="touchUpInside" id="C2I-4S-8ES"/>
                                </connections>
                            </button>
                            <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="XxV-Qs-KKx">
                                <rect key="frame" x="137" y="20" width="46" height="30"/>
                                <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                                <state key="normal" title="撤销">
                                    <color key="titleColor" red="0.3000516782" green="0.0" blue="1" alpha="1" colorSpace="calibratedRGB"/>
                                    <color key="titleShadowColor" white="0.5" alpha="1" colorSpace="calibratedWhite"/>
                                </state>
                                <connections>
                                    <action selector="removeOnClick" destination="vXZ-lx-hvc" eventType="touchUpInside" id="NY8-UW-wza"/>
                                </connections>
                            </button>
                        </subviews>
                        <color key="backgroundColor" red="1" green="0.54953925280000004" blue="0.292054386" alpha="1" colorSpace="calibratedRGB"/>
                    </view>
                    <connections>
                        <outlet property="drawingView" destination="O12-F5-sTX" id="ftL-w3-dLx"/>
                    </connections>
                </viewController>
                <placeholder placeholderIdentifier="IBFirstResponder" id="x5A-6p-PRh" sceneMemberID="firstResponder"/>
            </objects>
        </scene>
    </scenes>
    <simulatedMetricsContainer key="defaultSimulatedMetrics">
        <simulatedStatusBarMetrics key="statusBar"/>
        <simulatedOrientationMetrics key="orientation"/>
        <simulatedScreenMetrics key="destination"/>
    </simulatedMetricsContainer>
</document>

LWTViewController.h

#import <UIKit/UIKit.h>

@interface LWTViewController : UIViewController

@end

LWTViewController.m

//
//  LWTViewController.m
//  画画板
//
//  Created by apple on 14-6-12.
//  Copyright (c) 2014年 lwt. All rights reserved.
//

#import "LWTViewController.h"
#import "LWTView.h"
#import "MBProgressHUD+NJ.h"
#import "UIImage+captureView.h"

@interface LWTViewController ()
/**
 *  清屏
 */
- (IBAction)clearOnClick;
/**
 *  回退
 */
- (IBAction)removeOnClick;
/**
 *  保存
 */
- (IBAction)saveOnClick;

@property (weak, nonatomic) IBOutlet LWTView *drawingView;
@end

@implementation LWTViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (IBAction)clearOnClick {
    [self.drawingView clearPaths];
}

- (IBAction)removeOnClick {
    [self.drawingView removeLastPath];
}

- (IBAction)saveOnClick {
    
    UIImage *image = [UIImage captureImageWithView:self.drawingView];
    // 保存到相册
    UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
}

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    if (error) {
        [MBProgressHUD showError:@"保存失败"];
    }else
    {
        [MBProgressHUD showSuccess:@"保存成功"];
    }
}
@end

LWTView.h

#import <UIKit/UIKit.h>

@interface LWTView : UIView

- (void)clearPaths;

- (void)removeLastPath;

@end

LWTView.m

//
//  LWTView.m
//  画画板
//
//  Created by apple on 14-6-12.
//  Copyright (c) 2014年 lwt. All rights reserved.
//

#import "LWTView.h"


@interface LWTView ()

@property (nonatomic, strong) NSMutableArray *paths;

@end

@implementation LWTView

- (NSMutableArray *)paths
{
    if (!_paths) {
        _paths = [NSMutableArray array];
    }
    return _paths;
}

// 开始触摸
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    // 获取手指触摸的位置
    CGPoint startPoint = [self getCurrentPointWithTouchPoint:touches];
    
    // 当用户手指按下的时候创建一条路径
    UIBezierPath *path = [UIBezierPath  bezierPath];
    
    // 设置当前路径的起点
    [path moveToPoint:startPoint];
    // 设置路径的相关属性
    [path setLineCapStyle:kCGLineCapRound];
    [path setLineJoinStyle:kCGLineJoinRound];
    [path setLineWidth:3.0];
    
    // 将路径添加到数组中
    [self.paths addObject:path];
}

// 移动
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    // 获取手指触摸的位置
    CGPoint movePoint = [self getCurrentPointWithTouchPoint:touches];
    
    // 取出当前的path
    UIBezierPath *path = [self.paths lastObject];
    // 设置当前路径的终点
    [path addLineToPoint:movePoint];
    
    // 调用drawRect方法重回视图
    [self setNeedsDisplay];
}

// 离开view(停止触摸)
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    [self touchesMoved:touches withEvent:event];
}

- (CGPoint)getCurrentPointWithTouchPoint : (NSSet *)touches
{
    // 获取手指对应UITouch对象
    UITouch *touch = [touches anyObject];
    // 通过UITouch对象获取手指触摸的位置
    CGPoint point = [touch locationInView:touch.view];
    return point;
}

- (void)drawRect:(CGRect)rect
{
    [[UIColor cyanColor] set];
    // Drawing code
    // 遍历数组绘制所有的线段
    for (UIBezierPath *path in self.paths) {
        [path stroke];
    }
}

- (void)clearPaths
{
    [self.paths removeAllObjects];
    [self setNeedsDisplay];
}

- (void)removeLastPath
{
    [self.paths removeLastObject];
    [self setNeedsDisplay];
}

@end

UIImage+captureView.h

#import <UIKit/UIKit.h>

@interface UIImage (captureView)

+ (UIImage *)captureImageWithView : (UIView *)view;

@end

UIImage+captureView.m

//
//  UIImage+captureView.m
//  画画板
//
//  Created by apple on 14-6-12.
//  Copyright (c) 2014年 lwt. All rights reserved.
//

#import "UIImage+captureView.h"

@implementation UIImage (captureView)

+ (UIImage *)captureImageWithView:(UIView *)view
{
    // 创建bitmap上下文
    UIGraphicsBeginImageContext(view.bounds.size);
    // 将要保存的view的layer绘制到bitmap上下文中
    [view.layer renderInContext:UIGraphicsGetCurrentContext()];
    // 取出绘制号的图片
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    
    return image;
}

@end