问题描述
如何让用户从 Apple 照片库中选择照片?我们如何显示系统相机 UI 以允许用户拍照?
How can I let a user select a photo from the Apple Photos library? How do we show the system camera UI to allow the user to take a picture?
推荐答案
2016 年 3 月 15 日 - 这是我之前回答的 swift 版本,如果你正在寻找 Objective-c 版本,你会找到它下面.
March 15, 2016 - Here is a swift version of my prior answer, if you're looking for the objective-c version you'll find it below.
-- 斯威夫特--
首先符合 UIImagePickerControllerDelegate 协议和 UINavigationControllerDelegate 协议
First conform to the UIImagePickerControllerDelegate protocol and the UINavigationControllerDelegate protocol
class ViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate
启动图像选择器
func actionLaunchCamera()
{
if UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.Camera)
{
let imagePicker:UIImagePickerController = UIImagePickerController()
imagePicker.delegate = self
imagePicker.sourceType = UIImagePickerControllerSourceType.Camera
imagePicker.allowsEditing = true
self.presentViewController(imagePicker, animated: true, completion: nil)
}
else
{
let alert:UIAlertController = UIAlertController(title: "Camera Unavailable", message: "Unable to find a camera on this device", preferredStyle: UIAlertControllerStyle.Alert)
self.presentViewController(alert, animated: true, completion: nil)
}
}
实现 UIImagePickerDelegate 协议的委托方法
implement the delegate methods for UIImagePickerDelegate protocol
func imagePickerController(picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : AnyObject])
{
// create a filepath with the current date/time as the image name
let savePath:String = self.documentsPath()! + "/" + self.presentDateTimeString() + ".png"
// try to get our edited image if there is one, as well as the original image
let editedImg:UIImage? = info[UIImagePickerControllerEditedImage] as? UIImage
let originalImg:UIImage? = info[UIImagePickerControllerOriginalImage] as? UIImage
// create our image data with the edited img if we have one, else use the original image
let imgData:NSData = editedImg == nil ? UIImagePNGRepresentation(editedImg!)! : UIImagePNGRepresentation(originalImg!)!
// write the image data to file
imgData.writeToFile(savePath, atomically: true)
// dismiss the picker
self.dismissViewControllerAnimated(true, completion: nil)
}
func imagePickerControllerDidCancel(picker: UIImagePickerController)
{
// picker cancelled, dismiss picker view controller
self.dismissViewControllerAnimated(true, completion: nil)
}
// added these methods simply for convenience/completeness
func documentsPath() ->String?
{
// fetch our paths
let paths = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true)
if paths.count > 0
{
// return our docs directory path if we have one
let docsDir = paths[0]
return docsDir
}
return nil
}
func presentDateTimeString() ->String
{
// setup date formatter
let dateFormatter:NSDateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "dd-MM-yyyy HH:mm:ss"
// get current date
let now:NSDate = NSDate()
// generate date string from now
let theDateTime = dateFormatter.stringFromDate(now)
return theDateTime
}
-- 目标-C--
更新以在尝试启动相机之前检查相机是否可用.还添加了显示如何将 png 照片保存到应用沙箱内的文档文件夹的代码.
Updated to check if camera is available before trying to launch it. Also added code showing how to save a png photo to the documents folder within the app sandbox.
试一试(假设使用 ARC).
Give this a try (this assumes using ARC).
在.h文件中符合委托协议:
In the .h file conform to the delegate protocol:
@interface MyViewController : UIViewController <UINavigationControllerDelegate,UIImagePickerControllerDelegate>
在 .m 文件中启动图像选择器(相机):
In the .m file launch the image picker (camera):
-(void)actionLaunchAppCamera
{
if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])
{
UIImagePickerController *imagePicker = [[UIImagePickerController alloc]init];
imagePicker.delegate = self;
imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
imagePicker.allowsEditing = YES;
[self presentModalViewController:imagePicker animated:YES];
}else{
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Camera Unavailable"
message:@"Unable to find a camera on your device."
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil, nil];
[alert show];
alert = nil;
}
}
然后实现委托协议来处理用户取消事件或保存/编辑/等照片.
Then implement the delegate protocols to handle a user cancel event or save/edit/etc the photo.
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
//This creates a filepath with the current date/time as the name to save the image
NSString *presentTimeStamp = [Utilities getPresentDateTime];
NSString *fileSavePath = [Utilities documentsPath:presentTimeStamp];
fileSavePath = [fileSavePath stringByAppendingString:@".png"];
//This checks to see if the image was edited, if it was it saves the edited version as a .png
if ([info objectForKey:UIImagePickerControllerEditedImage]) {
//save the edited image
NSData *imgPngData = UIImagePNGRepresentation([info objectForKey:UIImagePickerControllerEditedImage]);
[imgPngData writeToFile:fileSavePath atomically:YES];
}else{
//save the original image
NSData *imgPngData = UIImagePNGRepresentation([info objectForKey:UIImagePickerControllerOriginalImage]);
[imgPngData writeToFile:fileSavePath atomically:YES];
}
[self dismissModalViewControllerAnimated:YES];
}
-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
[self dismissModalViewControllerAnimated:YES];
}
还在编辑中添加:以下是 Utilities 类中引用它的方法,用于获取文档路径和当前日期/时间
ALSO ADDED INHere are the methods referenced it the Utilities class for getting the document path and current date/time
+(NSString *)documentsPath:(NSString *)fileName {
NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
return [documentsDirectory stringByAppendingPathComponent:fileName];
}
+(NSString *)getPresentDateTime{
NSDateFormatter *dateTimeFormat = [[NSDateFormatter alloc] init];
[dateTimeFormat setDateFormat:@"dd-MM-yyyy HH:mm:ss"];
NSDate *now = [[NSDate alloc] init];
NSString *theDateTime = [dateTimeFormat stringFromDate:now];
dateTimeFormat = nil;
now = nil;
return theDateTime;
}
这篇关于如何从照片库中选择图像并在应用程序中显示系统相机界面?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!