一、简单的拍照显示，或是从相册中直接选取照片
#import "ViewController.h"
@interface ViewController ()<UIImagePickerControllerDelegate,UINavigationControllerDelegate>{
UIImageView *imageView;
}
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
imageView = [[UIImageView alloc] initWithFrame:CGRectMake(20, 80, self.view.bounds.size.width-40, 300)];
imageView.backgroundColor = [UIColor grayColor];
[self.view addSubview:imageView];
UIButton *button = [UIButton buttonWithType:(UIButtonTypeCustom)];
button.frame = CGRectMake(100, 400, 100, 50);
button.backgroundColor = [UIColor redColor];
[button setTitle:@"相机" forState:UIControlStateNormal];
[button addTarget:self action:@selector(camera) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:button];
UIButton *mButton = [UIButton buttonWithType:(UIButtonTypeCustom)];
mButton.frame = CGRectMake(100, 470, 100, 50);
mButton.backgroundColor = [UIColor redColor];
[mButton setTitle:@"相册" forState:UIControlStateNormal];
[mButton addTarget:self action:@selector(photo) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:mButton];
}
- (void)camera {
//判断是否由摄像头
BOOL isCamera = [UIImagePickerController isCameraDeviceAvailable:(UIImagePickerControllerCameraDeviceRear)];
//UIImagePickerControllerCameraDeviceRear后置摄像头
//前置摄像头UIImagePickerControllerCameraDeviceFront
if (!isCamera) {
NSLog(@"没有后置摄像头");
return;
}
UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
imagePicker.delegate = self;
imagePicker.editing = YES;//相机照的照片是否允许编辑
[self presentViewController:imagePicker animated:YES completion:^{
}];
}
//调取相册
- (void)photo {
UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
imagePicker.delegate = self;
[self presentViewController:imagePicker animated:YES completion:nil];
}
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(NSDictionary *)editingInfo {
//选取相册照片
imageView.image = image;
[self dismissViewControllerAnimated:YES completion:nil];
}
@end
二、在一的基础上得到的照片要保存本地
1、保存
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(NSDictionary *)editingInfo {
[[NSUserDefaults standardUserDefaults] setObject:UIImagePNGRepresentation(image) forKey:@"userImage"];
[self dismissViewControllerAnimated:YES completion:nil];
}
2、取出
NSData* imageData = [[NSUserDefaults standardUserDefaults] objectForKey:@"userImage"];
UIImage *userImage = [UIImage imageWithData:imageData];
三、在二中取出的图片是有问题的。
一幅图片除了包含我们能看见的像素信息，背后还包含了拍摄时间，光圈大小，曝光等信息。UIImage类将这些细节信息都隐藏了起来，只提供我们关心的图片尺寸，图片方向等。用相机拍摄出来的照片含有EXIF信息，UIImage的imageOrientation属性指的就是EXIF中的orientation信息。如果我们忽略orientation信息，而直接对照片进行像素处理或者drawInRect等操作，得到的结果是翻转或者旋转90之后的样子。这是因为我们执行像素处理或者drawInRect等操作之后，imageOrientaion信息被删除了，imageOrientaion被重设为0，造成照片内容和imageOrientaion不匹配。
目前市面上的大部分数码相机和手机都会内置一个方向感应器，拍出的照片中会写如方向信息，但是通常都只会有前四种方向。这几种Mirrored方向通常都是手机前置摄像头自拍的时候才会设置。
enum {
exifOrientationUp = 1, // UIImageOrientationUp
exifOrientationDown = 3, // UIImageOrientationDown
exifOrientationLeft = 6, // UIImageOrientationLeft
exifOrientationRight = 8, // UIImageOrientationRight
// these four exifOrientation does not support by all camera, but IOS support these orientation
exifOrientationUpMirrored = 2, // UIImageOrientationUpMirrored
exifOrientationDownMirrored = 4, // UIImageOrientationDownMirrored
exifOrientationLeftMirrored = 5, // UIImageOrientationLeftMirrored
exifOrientationRightMirrored = 7, // UIImageOrientationRightMirrored
};
typedef NSInteger ExifOrientation;
所以，在对照片进行保存之后，也需要将imageOrientaion这个代表方向的值保存起来，取出的时候再调整图片的方向。废话不多说了，上代码：
1、保存
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(NSDictionary *)editingInfo {
[[NSUserDefaults standardUserDefaults] setObject:UIImagePNGRepresentation(image) forKey:@"userImage"];
[[NSUserDefaults standardUserDefaults] setObject:[NSNumber numberWithInteger:image.imageOrientation] forKey:@"userImage_imageOrientation"];
[self dismissViewControllerAnimated:YES completion:nil];
}
2、取出
NSData* imageData = [[NSUserDefaults standardUserDefaults] objectForKey:@"userImage"];
UIImage *userImage = [UIImage imageWithData:imageData];
NSInteger imageOrientation = [[userDefault objectForKey:@"userImage_imageOrientation"] integerValue];
imageView.image = [self fixOrientationWithImage:userImage AndImageOrientation:imageOrientation];
//根据保存的方向值选择图片
- (UIImage *)fixOrientationWithImage:(UIImage *)aImage AndImageOrientation:(NSInteger)imageOrientation {
if (imageOrientation == UIImageOrientationUp)
return aImage;
CGAffineTransform transform = CGAffineTransformIdentity;
switch (imageOrientation) {
case UIImageOrientationDown:
case UIImageOrientationDownMirrored:
transform = CGAffineTransformTranslate(transform, aImage.size.width, aImage.size.height);
transform = CGAffineTransformRotate(transform, M_PI);
break;
case UIImageOrientationLeft:
case UIImageOrientationLeftMirrored:
transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);
transform = CGAffineTransformRotate(transform, M_PI_2);
break;
case UIImageOrientationRight:
case UIImageOrientationRightMirrored:
transform = CGAffineTransformTranslate(transform, 0, aImage.size.height);
transform = CGAffineTransformRotate(transform, -M_PI_2);
break;
default:
break;
}
switch (imageOrientation) {
case UIImageOrientationUpMirrored:
case UIImageOrientationDownMirrored:
transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);
transform = CGAffineTransformScale(transform, -1, 1);
break;
case UIImageOrientationLeftMirrored:
case UIImageOrientationRightMirrored:
transform = CGAffineTransformTranslate(transform, aImage.size.height, 0);
transform = CGAffineTransformScale(transform, -1, 1);
break;
default:
break;
}
CGContextRef ctx = CGBitmapContextCreate(NULL, aImage.size.width, aImage.size.height,
CGImageGetBitsPerComponent(aImage.CGImage), 0,
CGImageGetColorSpace(aImage.CGImage),
CGImageGetBitmapInfo(aImage.CGImage));
CGContextConcatCTM(ctx, transform);
switch (imageOrientation) {
case UIImageOrientationLeft:
case UIImageOrientationLeftMirrored:
case UIImageOrientationRight:
case UIImageOrientationRightMirrored:
CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.height,aImage.size.width), aImage.CGImage);
break;
default:
CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.width,aImage.size.height), aImage.CGImage);
break;
}
CGImageRef cgimg = CGBitmapContextCreateImage(ctx);
UIImage *img = [UIImage imageWithCGImage:cgimg];
CGContextRelease(ctx);
CGImageRelease(cgimg);
return img;
}