我制作了一个识别图像的AR应用程序，并显示AlertView中识别的对象。在AlertView中，我有2个按钮：添加和取消，我正在使用UIAlertViewDelegate来了解用户按下的按钮。如果用户按下“添加”按钮，则识别的对象将存储在数组中。我将此数组传递给另一个ViewController，我在其中设置了一个TableView。在这个TableView的底部有一个按钮“Pay”转到另一个ViewController，在其中我显示被识别对象的总价。从最后一个ViewController我可以按一个按钮来支付我使用AR选择的对象。现在，当我按下此按钮时，应用程序关闭此ViewController并返回到第一个ViewController，但是我在其中存储了AR识别出它的对象的数组。要删除这个数组的内容，我认为最好的方法是使用委托方法，所以我做了这个：
PaymentViewController.h
#import <UIKit/UIKit.h>
@protocol PaymentViewControllerDelegate;
@interface PaymentViewController : UIViewController
@property (strong, nonatomic) IBOutlet UILabel *labelTotal;
- (IBAction)buttonClosePaymentVC:(id)sender;
- (IBAction)buttonPay:(id)sender;
@property(nonatomic,strong)NSString *total;
@property(assign) id<PaymentViewControllerDelegate> delegate;
@end
@protocol PaymentViewControllerDelegate <NSObject>
- (void)cleanReportArray;
@end
PaymentViewController.m
#import "PaymentViewController.h"
@interface PaymentViewController () <UIAlertViewDelegate>
@end
@implementation PaymentViewController
@synthesize delegate = _delegate;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.labelTotal.text = self.total;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)buttonClosePaymentVC:(id)sender {
[self dismissViewControllerAnimated:YES completion:nil];
}
- (IBAction)buttonPay:(id)sender {
NSString *pay = [NSString stringWithFormat:@"Stai per pagare %@, procedi?", self.total];
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"HelloMS" message:pay delegate:self cancelButtonTitle:@"Si" otherButtonTitles:@"No", nil];
[alert show];
}
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
if (buttonIndex == 0) {
// Procedura per il pagamento e cancellazione del file plist
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *path = [documentsDirectory stringByAppendingPathComponent:@"objects.plist"];
NSError *error;
if (![[NSFileManager defaultManager]removeItemAtPath:path error:&error]) {
NSLog(@"Errore: %@", error);
}
__weak UIViewController *vcThatPresentedCurrent = self.presentingViewController;
[self dismissViewControllerAnimated:YES completion:^{
[vcThatPresentedCurrent dismissViewControllerAnimated:YES completion:nil];
}];
[self.delegate cleanReportArray];
}
if (buttonIndex == 1) {
// Non deve far nulla: fa scomparire l'UIAlertView
}
}
在这里，我向您发布将使用委托的类的方法：
ScannerViewController.m的界面
@interface ScannerViewController () <MSScannerSessionDelegate, PaymentViewControllerDelegate, UIActionSheetDelegate, UIAlertViewDelegate>
@property (weak) IBOutlet UIView *videoPreview;
- (IBAction)stopScanner:(id)sender;
@end
在ViewDidLoad我插入了这些行：
PaymentViewController *pay = [[PaymentViewController alloc]init];
[pay setDelegate:self];
在ScannerViewController.m我实现了我在PaymentViewController.h中声明的方法：
- (void)cleanReportArray {
[arrayObjectAdded removeAllObjects];
}
我在我的iPhone上测试了我的应用程序，该应用程序工作正常，直到我尝试支付我通过相机扫描的对象，实际上，我试图支付对象，但它不清理我存储对象的数组扫描。 我的代码有什么问题？我在网上使用了一个教程来更好地理解委托方法的工作原理。我希望你能帮我解决这个问题，谢谢
更新 在这里，我将发布我的ScannerViewController代码：
ScannerViewController.h
#import <UIKit/UIKit.h>
@interface ScannerViewController : UIViewController
@end
ScannerViewController.m
#import "ScannerViewController.h"
#import "PaymentViewController.h"
#import "ReportViewController.h"
#import "MSScannerSession.h"
#import "MSResult.h"
#import "XmlReader.h"
static int kMSScanOptions = MS_RESULT_TYPE_IMAGE |
MS_RESULT_TYPE_EAN8 |
MS_RESULT_TYPE_EAN13;
@interface ScannerViewController () <MSScannerSessionDelegate, PaymentViewControllerDelegate, UIActionSheetDelegate, UIAlertViewDelegate>
@property (weak) IBOutlet UIView *videoPreview;
- (IBAction)stopScanner:(id)sender;
@end
@implementation ScannerViewController {
MSScannerSession *_scannerSession;
NSString *nameOfObjectScanned;
XmlReader *reader;
NSMutableArray *arrayObjectAdded;
}
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
_scannerSession = [[MSScannerSession alloc] initWithScanner:[MSScanner sharedInstance]];
[_scannerSession setScanOptions:kMSScanOptions];
[_scannerSession setDelegate:self];
}
return self;
}
- (void)session:(MSScannerSession *)scanner didScan:(MSResult *)result {
if (!result) {
return;
}
[_scannerSession pause];
NSString *resultStr = nil;
if (result) {
switch ([result getType]) {
case MS_RESULT_TYPE_IMAGE:
resultStr = [NSString stringWithFormat:@"Immagine trovata: %@", [result getValue]];
break;
case MS_RESULT_TYPE_EAN8:
case MS_RESULT_TYPE_EAN13:
resultStr = [NSString stringWithFormat:@"EAN trovato: %@", [result getValue]];
break;
default:
break;
}
}
dispatch_async(dispatch_get_main_queue(), ^{
UIActionSheet *asView = [[UIActionSheet alloc]initWithTitle:resultStr delegate:self cancelButtonTitle:@"OK" destructiveButtonTitle:nil otherButtonTitles:nil, nil];
asView.actionSheetStyle = UIActionSheetStyleBlackTranslucent;
[asView showInView:self.view];
[self addObjectToList:resultStr];
});
}
- (void)addObjectToList:(NSString *)objectName {
// Ricerca dell'oggetto
NSString *object = [objectName substringFromIndex:18];
if ([object isEqualToString:@"Binario_con_coppia"]) {
[self showAlert:object];
}
if ([object isEqualToString:@"Dadi_colorati"]) {
[self showAlert:object];
}
if ([object isEqualToString:@"Dadi_rossi"]) {
[self showAlert:object];
}
if ([object isEqualToString:@"Bici_da_corsa"]) {
[self showAlert:object];
}
}
- (void)showAlert:(NSString*)name {
name = [name stringByReplacingOccurrencesOfString:@"_" withString:@" "];
nameOfObjectScanned = name;
NSString *message = [NSString stringWithFormat:@"Ho riconosciuto questo oggetto: %@, vuoi aggiungerlo al carrello?", name];
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"HelloMS" message:message delegate:self cancelButtonTitle:@"Aggiungi" otherButtonTitles:@"Annulla", nil];
[alert show];
}
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
if (buttonIndex == 0) {
NSLog(@"Aggiungi");
for (int i = 0; i < [reader.objArray count]; i++) {
if ([[reader.objArray[i]objectForKey:@"name"] isEqualToString:nameOfObjectScanned]) {
// Salvo il nome dell'oggetto trovato, il prezzo e la descrizione
NSString *name = [reader.objArray[i]objectForKey:@"name"];
NSString *desc = [reader.objArray[i]objectForKey:@"desc"];
NSString *price = [reader.objArray[i]objectForKey:@"price"];
NSDictionary *newObjectAdded = [[NSDictionary alloc]init];
newObjectAdded = @{@"name": name,
@"desc": desc,
@"price": price};
[arrayObjectAdded addObject:newObjectAdded];
}
}
} else {
NSLog(@"Annulla");
}
}
- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {
[_scannerSession resume];
}
- (void)viewDidLoad
{
[super viewDidLoad];
arrayObjectAdded = [[NSMutableArray alloc]init];
CALayer *videoPreviewLayer = [self.videoPreview layer];
[videoPreviewLayer setMasksToBounds:YES];
CALayer *captureLayer = [_scannerSession previewLayer];
[captureLayer setFrame:[self.videoPreview bounds]];
[videoPreviewLayer insertSublayer:captureLayer below:[[videoPreviewLayer sublayers] objectAtIndex:0]];
reader = [[XmlReader alloc]init];
[reader parseXml];
[_scannerSession startCapture];
PaymentViewController *pay = [[PaymentViewController alloc]init];
[pay setDelegate:self];
}
- (void)cleanReportArray {
[arrayObjectAdded removeAllObjects];
}
- (void)dealloc {
[_scannerSession stopCapture];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)stopScanner:(id)sender {
ReportViewController *reportVC = [[ReportViewController alloc]initWithNibName:@"ReportViewController" bundle:nil];
reportVC.reportArray = arrayObjectAdded;
[reportVC setModalTransitionStyle:UIModalTransitionStyleFlipHorizontal];
[self presentViewController:reportVC animated:YES completion:nil];
}
@end
要识别图片我正在使用此AR SDK。我希望你能帮助我理解我的问题在哪里
答案 0 :(得分：1)
您的问题是在viewDidLoad中您有代码：
PaymentViewController *pay = [[PaymentViewController alloc]init];
[pay setDelegate:self];
这是你在该方法中做的最后一件事。因此，您创建和设置委托的PaymentViewController实例会立即销毁（通过ARC）。
您需要修改代码，以便在屏幕上显示的setDelegate:的实际实例上调用PaymentViewController，因为这是需要使用委托的实例（它接收来自的回调）警报视图）。