UIImagePickerController—打开系统相册和相

效果：点击中间的图片按钮会提示打开相机或相册，点击相应照片可以编辑需要显示的内容大小，然后更换刚才图片按钮的图片

效果图 模拟器只支持相册 替换图片

import UIKit

class ViewController: UIViewController {
    
    
    @IBOutlet weak var uiimageButton: UIButton!
    
    @IBAction func btnAction(sender: UIButton) {
        let alertC = UIAlertController(title: "选择图像", message: nil, preferredStyle: .ActionSheet)
        //相册
        let action1 = UIAlertAction(title: "相册", style: .Default) { (_) in
            //打开相册
            self.openPhotograph()
        }
        //相机
        let action2 = UIAlertAction(title: "相相机", style: .Default) { (_) in
            //打开相机
            self.openCamera()
        }
        
        let action3 = UIAlertAction(title: "取消", style: .Cancel, handler: nil)
        alertC.addAction(action1)
        alertC.addAction(action2)
        alertC.addAction(action3)
        self.presentViewController(alertC, animated: true, completion: nil)
    }
}

//MARK: - 打开相册
extension ViewController{
    //MARK: - 打开相册
    func openPhotograph(){
        
        //1.创建图片选择器
        let imagePicker = UIImagePickerController()
        
        //2.设置
        //.Camera -> 使用相机拍摄
        //.PhotoLibrary -> 相册(相机拍摄得到的)
        //.SavedPhotosAlbum -> 图册(保存了的图片，范围比相册广)
        imagePicker.sourceType = .SavedPhotosAlbum
        
        //3.显示图片选择器
        self.presentViewController(imagePicker, animated: true, completion: nil)
        
        //4.设置代理
        //遵循
        //1.UIImagePickerControllerDelegate
        //2.UINavigationControllerDelegate
        imagePicker.delegate = self
        
        //5.设置可以编辑
        imagePicker.allowsEditing = true
    }
    
    //MARK: - 打开相机
    func openCamera(){
        //1.判断是否有相机
        //方法：是否能获得指定资源
        let haveCamera = UIImagePickerController.isSourceTypeAvailable(.Camera)
        if haveCamera == false{
            print("不支持相机")
            return
        }
        //2.创建图片选择器对象
        let imagePicker = UIImagePickerController()
        
        //3.设置资源类型为相机
        imagePicker.sourceType = .Camera
        
        //4.允许图片编辑
        imagePicker.allowsEditing = true
        
        //5.设置代理
        imagePicker.delegate = self
        //遵循协议同上边一样
        
        //6.显示图片选择器
        self.presentViewController(imagePicker, animated: true, completion: nil)
    }
}

extension ViewController:UIImagePickerControllerDelegate,UINavigationControllerDelegate{
    
    //选中相机或者相册中的一张图片后会自动调用
    //参数2:所选中媒体的所有信息列表
    func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject]) {
        //1.获取选中的图片的原图
        //获取字典key的方法
        //print(info)
        //UIImagePickerControllerOriginalImage -> 被选中的对象的字典key
        //UIImagePickerControllerEditedImage -> 编辑之后对象的字典key
        //let image1 = info["UIImagePickerControllerOriginalImage"] as! UIImage
        //获取编辑后的图片(框住的部分)
        let image2 = info["UIImagePickerControllerEditedImage"] as! UIImage
        
        //2.显示在按钮上
        uiimageButton.setImage(image2, forState: .Normal)
        
        //3.让图片选择器消失
        picker.dismissViewControllerAnimated(true, completion: nil)
    }
}