iOS UIImagePickerController 和 ModalViewController

Question

我编写了一段代码，它在基于 PhoneGap 的应用程序中运行。该代码有一个插件，当使用以下代码单击网页上的某个绑定(bind)按钮时，该插件会启动 UIImagePickerController。

PhotoSelectorCommand.h

#import <Foundation/Foundation.h>
#import "PhoneGapCommand.h"

@interface PhotoSelectorCommand : PhoneGapCommand<UINavigationControllerDelegate, UIImagePickerControllerDelegate>  {
    NSString *url;
    NSString *extra;
}

@property (nonatomic, copy) NSString *url;
@property (nonatomic, copy) NSString *extra;

- (void) startPhotoSelector:(NSMutableArray *)arguments withDict:(NSMutableDictionary *)options;
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info;
- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker;

@end

PhotoSelectorCommand.m

#import "PhotoSelectorCommand.h"
#import "PhoneGapViewController.h"
#import "PhotoUploaderViewController.h"

@implementation PhotoSelectorCommand

@synthesize url;
@synthesize extra;

- (void) startPhotoSelector:(NSMutableArray*)arguments withDict:(NSMutableDictionary*)options // args: url
{   
    NSUInteger argc = [arguments count];

    if (argc < 1) {
        return; 
    }
    self.url = [arguments objectAtIndex:0];
    if (argc > 1) {
        self.extra = [arguments objectAtIndex:1];   
    }

    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
    imagePicker.delegate = self;
    imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

    PhoneGapViewController* cont = (PhoneGapViewController *)[super appViewController];
    [cont presentModalViewController:imagePicker animated:YES];
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    //on selected

    [picker dismissModalViewControllerAnimated:YES];

    PhotoUploaderViewController *photoUploader = [PhotoUploaderViewController alloc];

    PhoneGapViewController* cont = (PhoneGapViewController *)[super appViewController];

    [cont presentModalViewController:photoUploader animated:YES];

    [photoUploader.view removeFromSuperview];
    [picker release];

    [picker.view removeFromSuperview];
    [picker release];
}

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
    //on cancel
    NSString *failureCallback = [NSString stringWithFormat:@"PhotoSelector._onError('%@');", @"No image selected."];
    [webView stringByEvaluatingJavaScriptFromString:failureCallback];

    [picker dismissModalViewControllerAnimated:YES];
    [picker.view removeFromSuperview];
    [picker release];
}

@end

PhotoSelectorViewController.h

#import <UIKit/UIKit.h>

@interface PhotoUploaderViewController : UIViewController {

}

@end

PhotoSelectorViewController.m

#import "PhotoSelectorViewController.h"

@implementation PhotoSelectorViewController

-(void)init {
}
- (void)viewDidLoad {
    [super viewDidLoad];
}
- (void)didReceiveMemoryWarning {
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];
}
- (void)viewDidUnload {
    [super viewDidUnload];
}
- (void)dealloc {
    [super dealloc];
}

@end

上面的代码一直有效，直到它显示 UIImagePickerController，用户可以在其中选择图像。一旦选择了任何图像， Controller 就会关闭，但不会像 UIImagePickerController 那样呈现另一个 View 。知道为什么吗？

Answer 1

我不知道你为什么要解雇选择器？只有在 Controller 被关闭后才会调用此方法。另外，您要释放两次选择器和 removerFromSuperView？请尝试使用以下代码并查看注释行。

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
    //on selected

   // [picker dismissModalViewControllerAnimated:YES]; you need not to do this

    PhotoUploaderViewController *photoUploader = [PhotoUploaderViewController alloc];

    PhoneGapViewController* cont = (PhoneGapViewController *)[super appViewController];

    [cont presentModalViewController:photoUploader animated:YES];

   // [photoUploader.view removeFromSuperview]; // where you have added this view?
   // [picker release]; //you do not own this object..

    //[picker.view removeFromSuperview]; // and ?
    //[picker release]; // same here
}