我如何确保 UIImagePickerController 始终返回方形图像？ WhatsApp 可以做到，但我还没有找到实现这一目标的方法。

它在我的应用程序中的表现如何(在 iOS 7 中构建)

应该如何(WhatsApp - iOS 6)

我的代码:

- (IBAction)showImagePicker:(id)sender {
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
    imagePicker.delegate = self;
    imagePicker.allowsEditing = YES;

    if ([sender tag] == 1) {
        imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
    }
    else {
        imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    }

    [self presentModalViewController:imagePicker animated:YES];
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
    _imageView.image = [info objectForKey:UIImagePickerControllerEditedImage];
    [self dismissModalViewControllerAnimated:YES];
}

最佳答案

要更改捕获图像的大小，您需要在 IB 的 UIImageView 中设置 View 模式以缩放以填充。然后当从库或相机中选择图像时，它会自动调整大小。你必须关闭自动布局，因为它不允许调整 ImageView 的大小。你的代码很好。总之，这里是您可以构建的示例应用程序代码，以便更好地理解它。

.h

#import <UIKit/UIKit.h>

@interface ImageTestViewController : UIViewController <UIImagePickerControllerDelegate, UINavigationControllerDelegate>

@property (strong, nonatomic) IBOutlet UIImageView *imageView;

- (IBAction)takePhoto:  (UIButton *)sender;
- (IBAction)selectPhoto:(UIButton *)sender;

@end

.m

#import "ImageTestController.h"

@interface ImageTestViewController ()

@end

@implementation ImageTestViewController

- (void)viewDidLoad {

    [super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.

    if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {

        UIAlertView *myAlertView = [[UIAlertView alloc] initWithTitle:@"Error"
                                                        message:@"Device has no camera"
                                                        delegate:nil
                                                        cancelButtonTitle:@"OK"
                                                        otherButtonTitles: nil];
        [myAlertView show];
    }
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
}

- (IBAction)takePhoto:(UIButton *)sender {
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.delegate = self;
    picker.allowsEditing = YES;
    picker.sourceType = UIImagePickerControllerSourceTypeCamera;

    [self presentViewController:picker animated:YES completion:NULL];
}

- (IBAction)selectPhoto:(UIButton *)sender {
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.delegate = self;
    picker.allowsEditing = YES;
    picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

    [self presentViewController:picker animated:YES completion:NULL];
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    UIImage *chosenImage = info[UIImagePickerControllerEditedImage];
    self.imageView.image = chosenImage;

    [picker dismissViewControllerAnimated:YES completion:NULL];
}

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

@end

在 ImageTestController Xib 或 Storyboard中的 View 中，放置两个按钮，一个用于每个操作，并在 IB 中创建必要的链接。然后放置一个 UIImageView 来填充 View 中您想要的任何大小。单击 UIImageView 并在属性检查器的 View 部分将模式更改为缩放以填充。关闭自动布局。尝试将图像添加到您的模拟器只是为了测试它。确保图像为横向尺寸。构建并运行，当您从图像库中选择图像时，它会自动调整为正方形或您设置的任何其他尺寸 UIImageView。

我知道您了解上述大部分步骤，但我写这个答案不仅是为了帮助您解决问题，也是为了帮助其他可能有类似问题的人。希望它能帮助你。

关于iphone - 用 'UIImagePickerController' 和 'allowsEditing' 处理以获得完美的正方形，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/18429119/