iOS 取得单张系统图片

这里主要用到了UIImagePickerController

不多废话，直接上代码

 //
 //  RootViewController.m
 //  GetImageFromPhotoAlbum
 //
 //  Created by 王云龙 on 16/1/18.
 //  Copyright © 2016年 王云龙. All rights reserved.
 //

 #import "RootViewController.h"
 #import "SecViewController.h"

 @interface RootViewController ()<UIActionSheetDelegate,UINavigationControllerDelegate, UIImagePickerControllerDelegate>

 {
     UIImageView *_imageView;
     UIImageView *_imageViewR;
 }

 @end

 @implementation RootViewController

 /**
  *  1.导航器
  *  2.UIImagePickerController
  *  3.iOS文件存取，沙盒机制
  */

 - (void)viewDidLoad
 {
     [super viewDidLoad];
     // Do any additional setup after loading the view.

 #pragma mark - 导航器设置
     [self.navigationController.navigationBar setTranslucent:NO];//设置navigationbar的半透明
     NSLog(@"frame = %@,bounds = %@",NSStringFromCGRect(self.view.frame),NSStringFromCGRect(self.view.window.bounds));
     self.title = @"navigationcontroller";//设置navigationbar上显示的标题
     [self.navigationController.navigationBar setBarTintColor:[UIColor purpleColor]];//设置navigationbar的颜色

     UIBarButtonItem *left = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(leftAction:)];
     self.navigationItem.leftBarButtonItem = left; //设置navigationbar左边按钮

     self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemCamera target:self action:@selector(rightAction:)];//设置navigationbar右边按钮
     [self.navigationController.navigationBar setTintColor:[UIColor whiteColor]];//设置navigationbar上左右按钮字体颜色

 #pragma mark - 画面初始化
     _imageViewR = [[UIImageView alloc]initWithFrame:CGRectMake(, , , )];
     _imageViewR.backgroundColor = [UIColor grayColor];
     [self.view addSubview:_imageViewR];

     _imageView = [[UIImageView alloc]initWithFrame:CGRectMake(, , self.view.frame.size.width-, self.view.frame.size.width-)];
     _imageView.backgroundColor = [UIColor grayColor];
     [self.view addSubview:_imageView];

     UIButton *btn = [UIButton buttonWithType:UIButtonTypeSystem];
     btn.frame = CGRectMake(, CGRectGetMaxY(_imageView.frame)+, self.view.frame.size.width-, );
     btn.layer.cornerRadius = ;
     btn.layer.masksToBounds = YES;
     [btn setTitle:@"获取相册图片" forState:UIControlStateNormal];
     [btn addTarget:self action:@selector(btnAction:) forControlEvents:UIControlEventTouchUpInside];
     [self.view addSubview:btn];

 }

 #pragma mark - 导航控制器的跳转
 -(void)leftAction:(UIBarButtonItem*)sender{
     //只能跳到没有没有导航控制器的controller
     SecViewController *secVC = [[SecViewController alloc]init];
     [self.navigationController pushViewController:secVC animated:YES];
 }

 -(void)rightAction:(UIBarButtonItem*)sender{
     //相册
     UIImagePickerController *imagePickController = [[UIImagePickerController alloc]init];
     imagePickController.delegate = self;
     imagePickController.allowsEditing = YES;
     imagePickController.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
     [self presentViewController:imagePickController animated:YES completion:nil
      ];

 }

 #pragma mark - 相册中取得图片并显示
 -(void)btnAction:(UIButton*)sender{

     UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"获取图片" message:nil preferredStyle:UIAlertControllerStyleActionSheet];

     //判断支持类型
     //相册和图库的区别
     //http://zhidao.baidu.com/link?url=DGZvUPsBPpArTyqP5ff2BcbVL1s_OUuH9A4TfB3Bn0xTP_iylo7Y45wAShBGZXDW85cicNPaeXSQlLiPzYCvCbDmA9gPHX5042sNfrN5ZFu

     if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])
         NSLog(@"支持相机");
     else
         NSLog(@"不支持相机");

     if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary])
         NSLog(@"支持图库");
     else
         NSLog(@"不支持图库");

     if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeSavedPhotosAlbum])
         NSLog(@"支持相册");
     else
         NSLog(@"不支持相册");

     //判断是否支持相机
     if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
         UIAlertAction*defualtAction = [UIAlertAction actionWithTitle:@"拍照" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
             UIImagePickerController *imagePickerController = [[UIImagePickerController alloc]init];
             imagePickerController.delegate = self;
             imagePickerController.allowsEditing = YES;
             imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera;
             [self presentViewController:imagePickerController animated:YES completion:^{}];
         }];
         [alertController addAction:defualtAction];
     }
     UIAlertAction *defaultAction1 = [UIAlertAction actionWithTitle:@"从相册选择" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
         //相册
         UIImagePickerController *imagePickController = [[UIImagePickerController alloc]init];
         imagePickController.delegate = self;
         imagePickController.allowsEditing = YES;
         imagePickController.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
         [self presentViewController:imagePickController animated:YES completion:nil
          ];

     }];
     UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:nil];
     [alertController addAction:cancelAction];
     [alertController addAction:defaultAction1];

     //弹出视图
     [self presentViewController:alertController animated:YES completion:nil];

 }

 #pragma mark - 文件保存到本地
 //http://blog.csdn.net/jianjianyuer/article/details/8556024
 -(void)saveImage:(UIImage*)currentImage withName:(NSString*)name{
     //图片读取的两个方法
     //http://blog.csdn.net/lovenjoe/article/details/7484217
     //NSData存储二进制数据
     //http://blog.csdn.net/jjmm2009/article/details/39004149
     NSData *imageData = UIImagePNGRepresentation(currentImage);

     //沙盒介绍
     //http://www.cnblogs.com/taintain1984/archive/2013/03/19/2969201.html
     NSString *fullPath = [[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"]stringByAppendingPathComponent:name];

     //沙盒文件操作
     //http://www.cocoachina.com/bbs/read.php?tid-78784.html

     //将图片写入
     [imageData writeToFile:fullPath atomically:YES];
 }

 #pragma mark - UIImagePickerController的代理方法。
 -(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info{

     [picker dismissViewControllerAnimated:YES completion:nil];
     //得到原始图片，未编辑的
     UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];

     //判断是否图片已经读取过
     NSString*referenceURL = [info objectForKey:UIImagePickerControllerReferenceURL];
     NSLog(@"%@",referenceURL);
     //保存图片到本地
     //文件名为时间戳，防止重名
     NSDate *datenow = [NSDate date];
     NSString *timeSp = [NSString stringWithFormat:@"%lf",[datenow timeIntervalSince1970]];
     NSString *fileName = [NSString stringWithFormat:@"%@.png",timeSp];

     [self saveImage:image withName:fileName];

     NSString *fullPath = [[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"]stringByAppendingPathComponent:fileName];

     UIImage *saveImage = [[UIImage alloc]initWithContentsOfFile:fullPath];

     //设置图片显示
     [_imageView setImage:saveImage];
     [_imageViewR setImage:image];
 }

 -(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{
     [picker dismissViewControllerAnimated:YES completion:nil];
 }

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

 @end

取得图片的代码

注意点

需要设置的三个重要属性

delegate:代理，必须设置，否则选择图片后页面跳转不会来，也取不到选取的图片

allowEditing:最好设置为yes，否则看不到原图，只能在图片墙上选取图片

souceType:图片来源，有三个，照片流，图库，相机，区别和用法请参考代码

两个重要的代理方法

请参考代码，但是两个代理方法中都要写模态跳转，系统是不会自己跳回来的。