UIViewController 无法识别方法

Question

请帮我解决这个问题

我在名为 firstviewcontroller 的导航堆栈中有一个视图控制器

FirstViewController.h

@class ImperialPickerController;
@class FractionPickerController;
@class MetricPickerController;

@interface FirstViewController : UIViewController {

    UIView *pickerViewContainer;

    ImperialPickerController *ImperialPickerController;
    FractionPickerController *FractionPickerController;
    MetricPickerController *MetricPickerController;

    UIView *ImperialPickerViewContainer;
    UIView *FractionPickerViewContainer;
    UIView *MetricPickerViewContainer;

    UISegmentedControl *segmentedControl;

    NSInteger selectedUnit;
}

@property(nonatomic,retain) IBOutlet UIView *pickerViewContainer;

@property(nonatomic,retain) IBOutlet UIView *ImperialPickerViewContainer;
@property(nonatomic,retain) IBOutlet UIView *FractionPickerViewContainer;
@property(nonatomic,retain) IBOutlet UIView *MetricPickerViewContainer;

@property(nonatomic,retain) IBOutlet ImperialPickerController *ImperialPickerController;
@property(nonatomic,retain) IBOutlet FractionPickerController *FractionPickerController;
@property(nonatomic,retain) IBOutlet MetricPickerController *MetricPickerController;

@property(nonatomic,retain) IBOutlet UISegmentedControl *segmentedControl;

-(IBAction)toggleUnit;

@end

FirstViewController.m

@implementation FirstViewController

@synthesize ImperialPickerController;
@synthesize FractionPickerController;
@synthesize MetricPickerController;
@synthesize ImperialPickerViewContainer;
@synthesize FractionPickerViewContainer;
@synthesize MetricPickerViewContainer;
@synthesize pickerViewContainer;
@synthesize segmentedControl;

define METRIC_INDEX 0
define IMPERIAL_INDEX 1
define FRACTION_INDEX 2



-(IBAction)toggleUnit
{
    selectedUnit = [segmentedControl selectedSegmentIndex];

    if (selectedUnit == METRIC_INDEX)
    {
        [MetricPickerController updateLabel1];
    }

}
@end

MetricPickerController.h

@interface MetricPickerController : NSObject <UIPickerViewDataSource,UIPickerViewDelegate> {

    UIPickerView *pickerView;
    UILabel *label;
}
@property(nonatomic,retain)UIPickerView *pickerView;
@property(nonatomic,retain)UILabel *label;

-(void)updateLabel1;

@end

MetricPickerController.m

import "MetricPickerController.h"

@implementation MetricPickerController

@synthesize pickerView;
@synthesize label;


-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 2;
}

-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component

{
    return 10;
}

-(void)updateLabel1
{
    label.text = @"test"
}

问题是我在 firstviewcontroller 中编译时收到错误消息

-(IBAction)toggleUnit
{
    selectedUnit = [segmentedControl selectedSegmentIndex];

    if (selectedUnit == METRIC_INDEX)
    {
        [MetricPickerController updateLabel1]; <<<<< (MetricPickerController might not respond to +updateLabel1)!!
also if i click the toggle in IB xcode will crash with sigbart error 
    }

任何人都可以请帮助并建议我做错了什么我认为我已经正确连接了所有内容，所以我想这与我的方法声明有关

我知道代码在这个阶段是不完整的，但它让我疯狂地试图摆脱这个错误，我希望你能理解我只是一个学习者

}

Answer 1

问题在于updateLabel1 是一个实例方法，而您将其发送到一个类（错误消息中的+updateLabel1 而非-updateLabel1 告诉您这一点）。

由于您已将实例变量命名为与类相同，因此您应该可以通过编写来解决这个问题

[self.MetricPickerController updateLabel1];

相反 - 这让编译器清楚您指的是实例变量而不是实际的类。