NSUserDefault更新公式

Question

请问如何通过NSUserDefault更新我的公式。所以我有两个文本字段需要保持我的公式uptodate。所以用户输入数字（值），然后该数字需要去我的公式，但公式只显示距离值:)。

Answer 1

我试着用一些改变你的代码。这里是我的.h文件和.m文件。尝试这个。现在我也不明白你想要找出什么，但是这段代码给我的值不是nan。在编写代码时，不要忘记以小写字母开始变量名称，这是一种标准方式。如果将变量设置为属性，也可以使用self。

ViewController.h

#import <UIKit/UIKit.h> 
#import <MapKit/MapKit.h> 
#import <CoreLocation/CoreLocation.h> 

@interface ViewController : UIViewController 
<UITextFieldDelegate,CLLocationManagerDelegate>{ 
    IBOutlet MKMapView *mapView; 
    IBOutlet UITextField *textGas; 
    IBOutlet UITextField *textMoney; 
    IBOutlet UITextField *textTotal; 
    IBOutlet UITextField *textDistance; 
} 

@property (nonatomic, retain) CLLocationManager *locationManager; 
@end 

ViewController.m

#import "ViewController.h" 



    @interface ViewController() 
    { 
     double totalDistance; 
     float gas,money; 
    } 
    @end 

    @implementation ViewController 
    @synthesize locationManager; 


    - (void)viewDidLoad 
    { 
     [super viewDidLoad]; 
     self.locationManager = [[CLLocationManager alloc] init]; 
     self.locationManager.delegate = self; 
     self.locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters; 
     [self.locationManager startUpdatingLocation]; 

//set default value for Gas 
     if (![[NSUserDefaults standardUserDefaults] objectForKey:@"Gas"]) { 
      [[NSUserDefaults standardUserDefaults] setObject:@"1.0" forKey:@"Gas"]; 
      [[NSUserDefaults standardUserDefaults] synchronize]; 
     } 

//set default value for Money 
     if (![[NSUserDefaults standardUserDefaults] objectForKey:@"Money"]) { 
      [[NSUserDefaults standardUserDefaults] setObject:@"1.0" forKey:@"Money"]; 
      [[NSUserDefaults standardUserDefaults] synchronize]; 
     } 

     gas = [[[NSUserDefaults standardUserDefaults] objectForKey:@"Gas"] floatValue]; 
     money = [[[NSUserDefaults standardUserDefaults] objectForKey:@"Money"] floatValue]; 

     textGas.text = [NSString stringWithFormat:@"%.1f",gas]; 
     textMoney.text = [NSString stringWithFormat:@"%.1f",money]; 

     // Do any additional setup after loading the view, typically from a nib. 
    } 

    -(void)viewDidAppear:(BOOL)animated 
    { 
     [super viewDidAppear:animated]; 
     if ([[NSUserDefaults standardUserDefaults] objectForKey:@"Gas"]) 
      textGas.text = [[NSUserDefaults standardUserDefaults] objectForKey:@"Gas"]; 
     else 
      textGas.text = @"0";//set default value 

     if ([[NSUserDefaults standardUserDefaults] objectForKey:@"Money"]) 
      textMoney.text = [[NSUserDefaults standardUserDefaults] objectForKey:@"Money"]; 
     else 
      textMoney.text = @"0.01";//set default value 



    } 

    -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event 
    { 
     [textMoney resignFirstResponder]; 
     [textGas resignFirstResponder]; 
    } 

    - (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex 
    { 
     if (buttonIndex == 1) 
     { 
      exit(0); 
     } 
     if (buttonIndex == 0) { 
      [self.locationManager stopUpdatingLocation]; 
      mapView.showsUserLocation = NO; 
     } 

    } 
    #pragma mark - UITextFieldDelegate 
    -(void)textFieldDidEndEditing:(UITextField *)textField 
    { 

     if ([textField.text intValue] == 0) { 
      textGas.text = [NSString stringWithFormat:@"%.1f",gas]; 
      textMoney.text = [NSString stringWithFormat:@"%.1f",money]; 
      UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"" 
                  message:@"Value cann't be zero." 
                  delegate:self 
                cancelButtonTitle:@"OK" 
                otherButtonTitles:nil]; 
      [alert show]; 
      alert = nil; 
      return; 
     } 

     if (![textField.text length]) { 
      textGas.text = [NSString stringWithFormat:@"%.1f",gas]; 
      textMoney.text = [NSString stringWithFormat:@"%.1f",money]; 
      UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"" 
                  message:@"Value cann't be empty." 
                  delegate:self 
                cancelButtonTitle:@"OK" 
                otherButtonTitles:nil]; 
      [alert show]; 
      alert = nil; 
      return; 
     } 

     NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults]; 
     if (textField == textGas) { 
      [defaults setObject:textGas.text forKey:@"Gas"]; 
      gas = [textGas.text floatValue]; 
     } 
     else if (textField == textMoney) 
     { 
      [defaults setObject:textMoney.text forKey:@"Money"]; 
      money = [textMoney.text floatValue]; 
     } 
     [defaults synchronize]; 
    } 

    - (BOOL) textFieldShouldReturn:(UITextField *)textField 
    { 
     [textField resignFirstResponder]; 
     return YES; 
    } 

    #pragma mark - 
    #pragma mark CLLocationManagerDelegate Methods 

    - (void)locationManager:(CLLocationManager *)manager 
     didUpdateToLocation:(CLLocation *)newLocation 
       fromLocation:(CLLocation *)oldLocation { 
     { 
      // Zoom to the current user location. 
      MKCoordinateRegion userLocation = MKCoordinateRegionMakeWithDistance(newLocation.coordinate, 1200.0, 1200.0); 
      [mapView setRegion:userLocation animated:NO]; 
      mapView.showsUserLocation = YES; 
     } 



     if (!oldLocation) 
      totalDistance = 0.0; 
     else 
      totalDistance += [newLocation distanceFromLocation:oldLocation]; 


     double distance = totalDistance*0.00062137119; 
     textTotal.text = [[ NSString alloc] initWithFormat:@"$%.2f", distance/gas*money]; 
     textDistance.text = [NSString stringWithFormat:@"%.2f Miles", distance]; 

    } 


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

而且结果模拟器是

不要忘记从界面生成器连接delegates和IBOutlet。

Answer 2

我认为这个问题可能在于这里：

int gas = [[NSUserDefaults standardUserDefaults] objectForKey:@"Gas"]; 
int money = [[NSUserDefaults standardUserDefaults] objectForKey:@"Money"]; 

您从textField.text与0.00格式写出你NSUserDefaults直接，经常，但你在阅读它作为一个int。它可能被存储为NSString。您应该将其作为NSNumber进行存储和读取。

打算在：

NSNumber *foo = [NSNumber numberWithInteger:TextGas.text.integerValue]; 
NSNumber *bar = [NSNumber numberWithDouble:TextMoney.text.doubleValue];  
[defaults setObject:foo forKey:@"Gas"]; 
[defaults setObject:bar forKey:@"Money"]; 

走出：

NSNumber *gas = [[NSUserDefaults standardUserDefaults] objectForKey:@"Gas"]; 
NSNumber *money = [[NSUserDefaults standardUserDefaults] objectForKey:@"Money"]; 
gas.integerValue; 
money.doubleValue;