3个文本框和计算按钮

Question

我有3个文本框和一个计算按钮，我怎么能告诉按钮开关文本框被选中并将数字转换为其他文本框，我已经标记了文本框1,2和3，我是非常新的绿色编程，所以任何帮助都会很棒。这是我的代码

- (IBAction)Calculate:(id)sender {
    NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc] init];
    float a = [[numberFormatter numberFromString:_Barrels.text] floatValue];
    float b = [[numberFormatter numberFromString:_Gallons.text] floatValue];
    float c = [[numberFormatter numberFromString:_Liters.text] floatValue];

    _Barrels.text = [[NSString alloc]initWithFormat:@"% .2f", a];
    _Gallons.text = [[NSString alloc]initWithFormat:@"% .2f", a * 42];
    _Liters.text = [[NSString alloc]initWithFormat:@"% .2f", a * 159];
    _Barrels.text = [[NSString alloc]initWithFormat:@"% .2f", b * .0238];
    _Gallons.text = [[NSString alloc]initWithFormat:@"% .2f", b];
    _Liters.text = [[NSString alloc]initWithFormat:@"% .2f", b * 3.785];
    _Barrels.text = [[NSString alloc]initWithFormat:@"% .2f", c * .0063];
    _Gallons.text = [[NSString alloc]initWithFormat:@"% .2f", c * .264];
    _Liters.text = [[NSString alloc]initWithFormat:@"% .2f", c];
    switch ([sender tag]) {
        case 1:
            [_Barrels resignFirstResponder];
            [_Gallons resignFirstResponder];
            [_Liters resignFirstResponder];
            break;
        default:
            break;
    } 

Answer 1

在ViewController.h文件中取一个变量/flag来存储最后选择的文本字段

#import <UIKit/UIKit.h>
@interface ViewController : UIViewController<UITextFieldDelegate>
{
    int textfieldFlag;
}
@end

在ViewController中。m文件实现textfieldDelegate方法

-(void)textFieldDidBeginEditing:(UITextField *)textField 
{     
    textfieldFlag=textField.tag;
}

then in ur

 - (IBAction)Calculate:(id)sender
{
   //ABove Code....   
    if(textfieldFlag==1){
    _Barrels.text = [[NSString alloc]initWithFormat:@"% .2f", a];
    _Gallons.text = [[NSString alloc]initWithFormat:@"% .2f", a * 42];
    _Liters.text = [[NSString alloc]initWithFormat:@"% .2f", a * 159];
   }
if(textfieldFlag==2){
    _Barrels.text = [[NSString alloc]initWithFormat:@"% .2f", b * .0238];
    _Gallons.text = [[NSString alloc]initWithFormat:@"% .2f", b];
    _Liters.text = [[NSString alloc]initWithFormat:@"% .2f", b * 3.785];
   }
if(textfieldFlag==3){
    _Barrels.text = [[NSString alloc]initWithFormat:@"% .2f", c * .0063];
    _Gallons.text = [[NSString alloc]initWithFormat:@"% .2f", c * .264];
    _Liters.text = [[NSString alloc]initWithFormat:@"% .2f", c];
   }
   //Below Code...

}

使用相应的textfieldFlag。

textfieldFlag将包含选定/编辑的最后一个文本字段的标志

Answer 2

当您点击计算按钮时，必须调用此方法:- (void)textFieldDidEndEditing:(UITextField *)textField。在这里，通过检查tagValue来确定您编辑了哪个文本字段，并据此进行计算。请确保添加文本字段的委托，否则- (void)textFieldDidEndEditing将不会被调用