iOS实现头像选取（照相或者图片库）、大小等比缩放、生成圆形头像

//弹出actionsheet。选择获取头像的方式
//从相册获取图片
-(void)takePictureClick:(UIButton *)sender
{
//    /*注：使用，需要实现以下协议：UIImagePickerControllerDelegate,
//     UINavigationControllerDelegate
//     */
//    UIImagePickerController *picker = [[UIImagePickerController alloc]init];
//    //设置图片源(相簿)
//    picker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
//    //设置代理
//    picker.delegate = self;
//    //设置可以编辑
//    picker.allowsEditing = YES;
//    //打开拾取器界面
//    [self presentViewController:picker animated:YES completion:nil];
UIActionSheet* actionSheet = [[UIActionSheet alloc]
initWithTitle:@"请选择文件来源"
delegate:self
cancelButtonTitle:@"取消"
destructiveButtonTitle:nil
otherButtonTitles:@"照相机",@"摄像机",@"本地相簿",@"本地视频",nil];
[actionSheet showInView:self.view];

}
#pragma mark -
#pragma UIActionSheet Delegate
- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{
NSLog(@"buttonIndex = [%d]",buttonIndex);
switch (buttonIndex) {
case 0://照相机
{
UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
imagePicker.delegate = self;
imagePicker.allowsEditing = YES;
imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
//            [self presentModalViewController:imagePicker animated:YES];
[self presentViewController:imagePicker animated:YES completion:nil];
}
break;
case 1://摄像机
{
UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
imagePicker.delegate = self;
imagePicker.allowsEditing = YES;
imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
imagePicker.videoQuality = UIImagePickerControllerQualityTypeLow;
//            [self presentModalViewController:imagePicker animated:YES];
[self presentViewController:imagePicker animated:YES completion:nil];
}
break;
case 2://本地相簿
{
UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
imagePicker.delegate = self;
imagePicker.allowsEditing = YES;
imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
//            [self presentModalViewController:imagePicker animated:YES];
[self presentViewController:imagePicker animated:YES completion:nil];
}
break;
case 3://本地视频
{
UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
imagePicker.delegate = self;
imagePicker.allowsEditing = YES;
imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
//            [self presentModalViewController:imagePicker animated:YES];
[self presentViewController:imagePicker animated:YES completion:nil];
}
break;
default:
break;
}
}

#pragma mark -
#pragma UIImagePickerController Delegate
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
if ([[info objectForKey:UIImagePickerControllerMediaType] isEqualToString:(__bridge NSString *)kUTTypeImage]) {
UIImage *img = [info objectForKey:UIImagePickerControllerEditedImage];
[self performSelector:@selector(saveImage:)  withObject:img afterDelay:0.5];
}
else if ([[info objectForKey:UIImagePickerControllerMediaType] isEqualToString:(__bridge NSString *)kUTTypeMovie]) {
NSString *videoPath = [[info objectForKey:UIImagePickerControllerMediaURL] path];
self.fileData = [NSData dataWithContentsOfFile:videoPath];
}
//    [picker dismissModalViewControllerAnimated:YES];
[picker dismissViewControllerAnimated:YES completion:nil];
}

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

- (void)saveImage:(UIImage *)image {
//    NSLog(@"保存头像！");
//    [userPhotoButton setImage:image forState:UIControlStateNormal];
BOOL success;
NSFileManager *fileManager = [NSFileManager defaultManager];
NSError *error;

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *imageFilePath = [documentsDirectory stringByAppendingPathComponent:@"selfPhoto.jpg"];
NSLog(@"imageFile->>%@",imageFilePath);
success = [fileManager fileExistsAtPath:imageFilePath];
if(success) {
success = [fileManager removeItemAtPath:imageFilePath error:&error];
}
//    UIImage *smallImage=[self scaleFromImage:image toSize:CGSizeMake(80.0f, 80.0f)];//将图片尺寸改为80*80
UIImage *smallImage = [self thumbnailWithImageWithoutScale:image size:CGSizeMake(93, 93)];
[UIImageJPEGRepresentation(smallImage, 1.0f) writeToFile:imageFilePath atomically:YES];//写入文件
UIImage *selfPhoto = [UIImage imageWithContentsOfFile:imageFilePath];//读取图片文件
//    [userPhotoButton setImage:selfPhoto forState:UIControlStateNormal];
self.img.image = selfPhoto;
}

// 改变图像的尺寸，方便上传服务器
- (UIImage *) scaleFromImage: (UIImage *) image toSize: (CGSize) size
{
UIGraphicsBeginImageContext(size);
[image drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}

//2.保持原来的长宽比，生成一个缩略图
- (UIImage *)thumbnailWithImageWithoutScale:(UIImage *)image size:(CGSize)asize
{
UIImage *newimage;
if (nil == image) {
newimage = nil;
}
else{
CGSize oldsize = image.size;
CGRect rect;
if (asize.width/asize.height > oldsize.width/oldsize.height) {
rect.size.width = asize.height*oldsize.width/oldsize.height;
rect.size.height = asize.height;
rect.origin.x = (asize.width - rect.size.width)/2;
rect.origin.y = 0;
}
else{
rect.size.width = asize.width;
rect.size.height = asize.width*oldsize.height/oldsize.width;
rect.origin.x = 0;
rect.origin.y = (asize.height - rect.size.height)/2;
}
UIGraphicsBeginImageContext(asize);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [[UIColor clearColor] CGColor]);
UIRectFill(CGRectMake(0, 0, asize.width, asize.height));//clear background
[image drawInRect:rect];
newimage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
return newimage;
}

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *imageFilePath = [documentsDirectory stringByAppendingPathComponent:@"selfPhoto.jpg"];
NSLog(@"imageFile->>%@",imageFilePath);
UIImage *selfPhoto = [UIImage imageWithContentsOfFile:imageFilePath];//
self.img.image = selfPhoto;
[self.img.layer setCornerRadius:CGRectGetHeight([self.img bounds]) / 2];  //修改半径，实现头像的圆形化
self.img.layer.masksToBounds = YES;