Question

我正在使用UIPickerView并尝试实现使用映射到第一个组件中所选值的数据加载第二个组件的功能。但是，我的第二个组件总是显示映射到我的第一个组件的第二行的值。

使用断点我注意到- (UIView *)pickerView:(UIPickerView *)iPickerView viewForRow:(NSInteger)iRow forComponent:(NSInteger)iComponent reusingView:(UIView *)iView方法正确传递了值。

请看看到目前为止我做了什么。我错过了什么吗？

#import "ViewController.h"
#import "ZXingObjC.h"

@interface ViewController ()

@property (nonatomic, assign) IBOutlet UITextField *barcodeTextField;
@property (nonatomic, assign) IBOutlet UIImageView *barcodeImageView;
@property (weak, nonatomic) IBOutlet UIScrollView *scrollview;
@property (nonatomic, strong) NSArray *barcodeTypes;
@property (nonatomic, strong) NSDictionary *barcodes;
@property (nonatomic, assign) NSInteger selectedBarcodeType;

@end


typedef enum {
    OneDBarcode = 0,
    TwoDBarcode
} BarcodeTypes;


@implementation ViewController

- (void)loadView {
    [super loadView];

    UITapGestureRecognizer *aTapInsideTableView = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTap:)];
    [aTapInsideTableView setCancelsTouchesInView:NO];
    [self.view addGestureRecognizer:aTapInsideTableView];
}


- (void)viewDidLoad {
    [super viewDidLoad];

    NSArray *twoDBarcodes = @[@"Aztec", @"DataMatrix", @"MaxiCode", @"PDF417", @"QRCode", @"RSS14", @"RSSExpanded"];
    NSArray *oneDBarcodes = @[@"Codabar", @"Code39", @"Code93", @"Code128", @"Ean8", @"Ean13", @"ITF", @"UPCA", @"UPCE", @"UPCEANExtension"];
    self.barcodes = @{@"1D Barcodes": oneDBarcodes, @"2D Barcodes": twoDBarcodes};

    self.barcodeTypes = @[@"Aztec", @"Codabar", @"Code39", @"Code93", @"Code128", @"DataMatrix", @"Ean8", @"Ean13", @"ITF", @"MaxiCode", @"PDF417", @"QRCode", @"RSS14", @"RSSExpanded", @"UPCA", @"UPCE", @"UPCE"];

    self.selectedBarcodeType = OneDBarcode;

    [self.scrollview setScrollEnabled:YES];
    [self.scrollview setContentSize:CGSizeMake(320.0, 750.0)];
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


- (IBAction)generateBarcode:(id)sender {
    UIImage *barcodeImage = [self barcodeImageForText:self.barcodeTextField.text];
    if (barcodeImage) {
        self.barcodeImageView.image = barcodeImage;
    }
}


- (IBAction)dismissView:(id)iSender {
    [self.navigationController dismissViewControllerAnimated:YES completion:nil];
}


- (UIImage *)barcodeImageForText:(NSString *)iBarcode {
    NSError* error = nil;
    ZXMultiFormatWriter* writer = [ZXMultiFormatWriter writer];
    ZXBitMatrix* result = [writer encode:iBarcode
                                  format:kBarcodeFormatQRCode
                                   width:500
                                  height:500
                                   error:&error];
    if (result) {
        CGImageRef image = [[ZXImage imageWithMatrix:result] cgimage];

        // This CGImageRef image can be placed in a UIImage, NSImage, or written to a file.

        return [UIImage imageWithCGImage:image];
    } else {
        NSString* errorMessage = [error localizedDescription];
        NSLog(@"Error: %@", errorMessage);
        return nil;
    }
}


- (void)handleTap:(UITapGestureRecognizer *)iRecognizer {
    if (self.barcodeTextField) {
        [self.barcodeTextField resignFirstResponder];
    }
}


#pragma mark - UIPickerViewDataSource methods

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)iPickerView {
    return self.barcodes.allKeys.count;
}


- (NSInteger)pickerView:(UIPickerView *)iPickerView numberOfRowsInComponent:(NSInteger)iComponent {
    NSArray *barcodeKeys = self.barcodes.allKeys;
    NSArray *barcodeValues = self.barcodes[barcodeKeys[iComponent]];

    if (iComponent == OneDBarcode) {
        return barcodeKeys.count;
    }

    return barcodeValues.count;
}


#pragma mark - UIPickerViewDelegate methods

- (UIView *)pickerView:(UIPickerView *)iPickerView viewForRow:(NSInteger)iRow forComponent:(NSInteger)iComponent reusingView:(UIView *)iView {
    UILabel *label = (UILabel *)iView;

    if (!label) {
        label = [[UILabel alloc] initWithFrame:CGRectMake(0.0f, 0.0f, self.view.frame.size.width, 60.0f)];
        label.backgroundColor = [UIColor clearColor];
        label.textAlignment = NSTextAlignmentCenter;
        label.adjustsFontSizeToFitWidth = YES;
    }

    NSArray *barcodeKeys = self.barcodes.allKeys;
    NSArray *barcodeValues = self.barcodes[barcodeKeys[iComponent]];

    NSString *labelText;

    if (iComponent == OneDBarcode) {
        labelText = barcodeKeys[iRow];
    } else if (iComponent == TwoDBarcode) {
        labelText = barcodeValues[iRow];
    }

    label.text = labelText;

    return label;
}


- (void)pickerView:(UIPickerView *)iPickerView didSelectRow:(NSInteger)iRow inComponent:(NSInteger)iComponent {
    [iPickerView reloadComponent:iComponent];

    if (iComponent == OneDBarcode) {
        self.selectedBarcodeType = OneDBarcode;
    } else {
        self.selectedBarcodeType = TwoDBarcode;
    }

    [iPickerView reloadAllComponents];
}

@end

Answer 1

代码有很多问题。当用户在选择器中选择一行时，如果用户在第一个组件中选择了值，则仅加载第二个组件。在任何情况下都不要重新加载。

在viewForRow方法中，您有两个问题：

字典没有订购，得到的密钥没有订单。但是数组中第一个组件的值，因此您可以通过索引访问它们。
您尝试访问barcodeValues是基于该组件。它应该基于第一个组件的选定索引。

无法根据UIPickerview中第一个组件的值重新加载第二个组件

1 个答案: