如何在objective-c的pickerView中实现多次转换

Posted 2023-02-24

【中文标题】如何在objective-c的pickerView中实现多次转换

【英文标题】：How to implement a multiple conversions in pickerView in objective-c

【发布时间】：2019-12-09 15:18:01

【问题描述】：

我正在尝试创建一个转换应用程序。我要转换三个单位：温度（华氏度、磅和英里到它们的公制对应物）。

我想使用选择器视图，但在将选择器视图连接到功能和实际选择每个单元时遇到了困难。

我已经能够在分段控件中实现这一点，但希望 pickerView 能够在未来添加更多转化。

谢谢！

ViewControlle.m

#import "ViewController.h"

@interface  ViewController ()
NSArray *devices;

@end

//CONVERSIONS

// convert pounds to kilograms
double convertLbsToKgs(double poundsValue)
double kilogramsValue;
kilogramsValue = poundsValue / 2.205;
return kilogramsValue;


//convert fahrenheit to celcius
double convertFarenheitToCelcius(double farenheitValue)
double celciusValue;
celciusValue = (farenheitValue - 32) * 0.555;
return celciusValue;


//convert miles to kilometers
double convertMilesToKilometers(double milesValue)
double kilometersValue;
kilometersValue = milesValue * 1.609;
return kilometersValue;


@implementation ViewController

- (void)viewDidLoad 
[super viewDidLoad];

devices = @[@"Pounds", @"Fahernheit", @"Miles"];
self.pickerView.dataSource = self;
self.pickerView.delegate = self;


// pickerView datascource & delegate methods
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
return 1;
 

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
return devices.count;


- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
return devices[row];


- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component

self.outputTextBox.text = devices[row];


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

@end

ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController<UIPickerViewDataSource, UIPickerViewDelegate>

@property (weak, nonatomic) IBOutlet UITextField *inputField;
@property (weak, nonatomic) IBOutlet UILabel *outputTextBox;
@property (weak, nonatomic) IBOutlet UIPickerView *pickerView;


@end

【问题讨论】：

我已经实现了相同的代码，我没有任何问题。请简要描述发生了什么。

我可以显示当前启用了哪一行，但我想执行一些函数来计算华氏度到摄氏度等。

【参考方案1】：

在 didselect 方法中添加此代码。

if ([devices[row]  isEqualToString: @"Pounds"]) 
           double kgs =[self convertLbsToKgs:[inputField.text doubleValue]];
            outputTextBox.text=[NSString stringWithFormat:@"%f",kgs];

        else if ([devices[row]  isEqualToString: @"Fahernheit"])
            double celcious =[self convertFarenheitToCelcius:[inputField.text doubleValue]];
            outputTextBox.text=[NSString stringWithFormat:@"%f",celcious];

        else if ([devices[row]  isEqualToString: @"Miles"])
            double kms=[self convertMilesToKilometers:[inputField.text doubleValue]];
            outputTextBox.text=[NSString stringWithFormat:@"%f",kms];