首先，添加UINavigationControllerDelegate和UIImagePickerControllerDelegate两项PRotocol.
　　使用UIImagePickerController，就必须实现UINavigationControllerDelegate这个protocol，因为调用过程中会出现NavigationBar,如果没实现，也不会说运行不了。只是Xcode会直接就给你一个warning.

　　直接上自己用swift写的一个设置头像的小demo，可直接复制使用。注释清晰明了。

  1 //
  2 //  ViewController.swift
  3 //  ImageDemo
  4 //
  5 //  Created by fanviwa on 15/4/22.
  6 //  Copyright (c) 2015年 fanviwa. All rights reserved.
  7 //
  8 
  9 import UIKit
 10 
 11 class ViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
 12     
 13     @IBOutlet weak var imageView: UIImageView!
 14      // 初始化图片选择控制器
 15     let imagePickerController: UIImagePickerController = UIImagePickerController()
 16     var isFullScreen: Bool = false
 17     
 18     override func viewDidLoad() {
 19         super.viewDidLoad()
 20         // Do any additional setup after loading the view, typically from a nib.
 21         self.imageView.frame = CGRectMake(100, 100, 128, 128)
 22     }
 23 
 24     override func didReceiveMemoryWarning() {
 25         super.didReceiveMemoryWarning()
 26         // Dispose of any resources that can be recreated.
 27     }
 28 
 29     @IBAction func chooseImage(sender: UIButton) {
 30         // 设置代理
 31         self.imagePickerController.delegate = self
 32         // 设置是否可以管理已经存在的图片或者视频
 33         self.imagePickerController.allowsEditing = true
 34 
 35         // 判断是否支持相机
 36         if(UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.Camera)){
 37             let alertController: UIAlertController = UIAlertController(title: nil, message: nil, preferredStyle: UIAlertControllerStyle.ActionSheet)
 38             //在ipad上使用表单（ActionSheet）需要设置描点(anchor point)
 39             var popover = alertController.popoverPresentationController
 40             if (popover != nil){
 41                 popover?.sourceView = sender
 42                 popover?.sourceRect = sender.bounds
 43                 popover?.permittedArrowDirections = UIPopoverArrowDirection.Any
 44             }
 45             
 46             let cameraAction: UIAlertAction = UIAlertAction(title: "拍照换头像", style: .Default) { (action: UIAlertAction!) -> Void in
 47                 // 设置类型
 48                 self.imagePickerController.sourceType = UIImagePickerControllerSourceType.Camera
 49                 self.presentViewController(self.imagePickerController, animated: true, completion: nil)
 50             }
 51             alertController.addAction(cameraAction)
 52             
 53             let photoLibraryAction: UIAlertAction = UIAlertAction(title: "从相册选择换头像", style: .Default) { (action: UIAlertAction!) -> Void in
 54                 // 设置类型
 55                 self.imagePickerController.sourceType = UIImagePickerControllerSourceType.PhotoLibrary
 56                 //改navigationBar背景色
 57                 self.imagePickerController.navigationBar.barTintColor = UIColor(red: 171/255, green: 202/255, blue: 41/255, alpha: 1.0)
 58                 //改navigationBar标题色
 59                 self.imagePickerController.navigationBar.titleTextAttributes = [NSForegroundColorAttributeName: UIColor.whiteColor()]
 60                 //改navigationBar的button字体色
 61                 self.imagePickerController.navigationBar.tintColor = UIColor.whiteColor()
 62                 self.presentViewController(self.imagePickerController, animated: true, completion: nil)
 63             }
 64             alertController.addAction(photoLibraryAction)
 65             
 66             let cancelAction: UIAlertAction = UIAlertAction(title: "取消", style: .Cancel, handler: nil)
 67             alertController.addAction(cancelAction)
 68             
 69             presentViewController(alertController, animated: true, completion: nil)
 70             
 71         }else{
 72             let alertController: UIAlertController = UIAlertController(title: nil, message: nil, preferredStyle: UIAlertControllerStyle.ActionSheet)
 73             //设置描点(anchor point)
 74             var popover = alertController.popoverPresentationController
 75             if (popover != nil){
 76                 popover?.sourceView = sender
 77                 popover?.sourceRect = sender.bounds
 78                 popover?.permittedArrowDirections = UIPopoverArrowDirection.Any
 79             }
 80             
 81             let photoLibraryAction: UIAlertAction = UIAlertAction(title: "从相册选择换头像", style: .Default) { (action: UIAlertAction!) -> Void in
 82                 // 设置类型
 83                 self.imagePickerController.sourceType = UIImagePickerControllerSourceType.PhotoLibrary
 84                 //改navigationBar背景色
 85                 self.imagePickerController.navigationBar.barTintColor = UIColor(red: 171/255, green: 202/255, blue: 41/255, alpha: 1.0)
 86                 //改navigationBar标题色
 87                 self.imagePickerController.navigationBar.titleTextAttributes = [NSForegroundColorAttributeName: UIColor.whiteColor()]
 88                 //改navigationBar的button字体色
 89                 self.imagePickerController.navigationBar.tintColor = UIColor.whiteColor()
 90                 self.presentViewController(self.imagePickerController, animated: true, completion: nil)
 91             }
 92             alertController.addAction(photoLibraryAction)
 93             
 94             let cancelAction: UIAlertAction = UIAlertAction(title: "取消", style: .Cancel, handler: nil)
 95             alertController.addAction(cancelAction)
 96             
 97             presentViewController(alertController, animated: true, completion: nil)
 98         }
 99     }
100 
101     //实现ImagePicker delegate 事件
102     func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [NSObject : AnyObject]) {
103         picker.dismissViewControllerAnimated(true, completion: nil)
104         var image: UIImage!
105         // 判断，图片是否允许修改
106         if(picker.allowsEditing){
107             //裁剪后图片
108             image = info[UIImagePickerControllerEditedImage] as! UIImage
109         }else{
110             //原始图片
111             image = info[UIImagePickerControllerOriginalImage] as! UIImage
112         }
113         /* 此处info 有六个值
114         * UIImagePickerControllerMediaType; // an NSString UTTypeImage)
115         * UIImagePickerControllerOriginalImage;  // a UIImage 原始图片
116         * UIImagePickerControllerEditedImage;    // a UIImage 裁剪后图片
117         * UIImagePickerControllerCropRect;       // an NSValue (CGRect)
118         * UIImagePickerControllerMediaURL;       // an NSURL
119         * UIImagePickerControllerReferenceURL    // an NSURL that references an asset in the AssetsLibrary framework
120         * UIImagePickerControllerMediaMetadata    // an NSDictionary containing metadata from a captured photo
121         */
122         // 保存图片至本地，方法见下文
123         self.saveImage(image, newSize: CGSize(width: 256, height: 256), percent: 0.5, imageName: "currentImage.png")
124         let fullPath: String = NSHomeDirectory().stringByAppendingPathComponent("Documents").stringByAppendingPathComponent("currentImage.png")
125         println("fullPath=\(fullPath)")
126         let savedImage: UIImage = UIImage(contentsOfFile: fullPath)!
127         self.isFullScreen = false
128         self.imageView.image = savedImage
129         //在这里调用网络通讯方法，上传头像至服务器...
130     }
131     // 当用户取消时，调用该方法
132     func imagePickerControllerDidCancel(picker: UIImagePickerController) {
133         self.dismissViewControllerAnimated(true, completion: nil)
134     }
135     
136     //保存图片至沙盒
137     func saveImage(currentImage: UIImage, newSize: CGSize, percent: CGFloat, imageName: String){
138         //压缩图片尺寸
139         UIGraphicsBeginImageContext(newSize)
140         currentImage.drawInRect(CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height))
141         let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()
142         UIGraphicsEndImageContext()
143         //高保真压缩图片质量
144         //UIImageJPEGRepresentation此方法可将图片压缩，但是图片质量基本不变，第二个参数即图片质量参数。
145         let imageData: NSData = UIImageJPEGRepresentation(newImage, percent)
146         // 获取沙盒目录,这里将图片放在沙盒的documents文件夹中
147         let fullPath: String = NSHomeDirectory().stringByAppendingPathComponent("Documents").stringByAppendingPathComponent(imageName)
148         // 将图片写入文件
149         imageData.writeToFile(fullPath, atomically: false)
150     }
151     
152     //实现点击图片预览功能，滑动放大缩小，带动画
153     override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
154         self.isFullScreen = !self.isFullScreen
155         
156         let touch: UITouch = touches.first as! UITouch
157         let touchPoint: CGPoint  = touch.locationInView(self.view)
158         let imagePoint: CGPoint = self.imageView.frame.origin
159         //touchPoint.x ，touchPoint.y 就是触点的坐标
160         // 触点在imageView内，点击imageView时 放大,再次点击时缩小
161         if(imagePoint.x <= touchPoint.x && imagePoint.x + self.imageView.frame.size.width >= touchPoint.x && imagePoint.y <=  touchPoint.y && imagePoint.y+self.imageView.frame.size.height >= touchPoint.y){
162             // 设置图片放大动画
163             UIView.beginAnimations(nil, context: nil)
164             // 动画时间
165             UIView.setAnimationDuration(1)
166             
167             if (isFullScreen) {
168                 // 放大尺寸
169                 self.imageView.frame = CGRectMake(0, 0, 480, 320)
170             }
171             else {
172                 // 缩小尺寸
173                 self.imageView.frame = CGRectMake(100, 100, 128, 128)
174             }
175             // commit动画
176             UIView.commitAnimations()
177         }
178     }
179 }

其次，还有一些检查是否有硬件的方法。

1 // 判断设备是否有摄像头
2     UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.Camera)
3     // 前面的摄像头是否可用
4     UIImagePickerController.isCameraDeviceAvailable(UIImagePickerControllerCameraDevice.Front)
5     // 后面的摄像头是否可用
6     UIImagePickerController.isCameraDeviceAvailable(UIImagePickerControllerCameraDevice.Rear)
7     // 相册是否可用
8     UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.PhotoLibrary)

当然，想要修改相册页面为中文还的在Info.plist配置文件中添加"Localized resources can be mixed"属性并设置为YES。

注意：iOS8.0后提示“

Snapshotting a view that has not been rendered results in an empty snapshot. Ensure your view has been rendered at least once before snapshotting or snapshot after screen updates.

”是正常的，暂无解决办法。

希望对你有帮助！