將數據傳遞給視圖控制器

Question

這裏是我傳遞數據的按鈕函數。

問題是區域和國家的詳細信息傳遞給下一個ViewController，但經度和緯度返回null。

在ViewController.m：

- (IBAction)forecast:(UIButton *)sender 
{ 
    ForecastViewController *sendDetails = [[ForecastViewController alloc] init]; 
    NSArray *seperate = [full componentsSeparatedByString:@", "]; 
    Area = seperate[0]; 
    Country = seperate[1]; 
    sendDetails.Area = Area; 
    sendDetails.Country = Country; 
    NSLog(@"%@%@",self.longitude,self.latitude); 
    NSString *lt = self.latitude; 
    NSString *ln = self.longitude; 
    sendDetails.longitude = lt; 
    sendDetails.latitude = ln; 
} 

在ForecastViewController.h

// 
// ForecastViewController.h 
// Weather App 
// 
// Created by Mac-Mini-2 on 10/02/16. 
// Copyright © 2016 Mac-Mini-2. All rights reserved. 
// 

#import <UIKit/UIKit.h> 
#import <CoreData/CoreData.h> 
#import <Reachability.h> 

@interface ForecastViewController : UIViewController <UITableViewDataSource,UITableViewDelegate> 

@property (weak, nonatomic) IBOutlet UILabel *place; 
@property (weak, nonatomic) IBOutlet UITableView *table; 
@property (weak, nonatomic) IBOutlet UIActivityIndicatorView *activityIndicator; 

@property NSString *Area; 
@property NSString *Country; 
@property NSString *latitude; 
@property NSString *longitude; 

@end 

在ForecastViewController.m

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    // Do any additional setup after loading the view. 
    self.table.delegate = self; 
    self.table.dataSource = self; 
    self.place.text = [NSString stringWithFormat:@"%@, %@",self.Area,self.Country]; 
    locationName = [NSString stringWithFormat:@"%@, %@",self.Area,self.Country]; 

    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults]; 
    metric = [defaults boolForKey:@"metric"]; 
    Reachability *reach = [Reachability reachabilityWithHostName:@"www.google.com"]; 
    NSInteger x = [reach currentReachabilityStatus]; 
    if (x > 0) 
    { 
     reachable = YES; 
     NSLog(@"%@, %@",self.latitude,self.longitude); 
     [self getForecast:self.latitude longitudes:self.longitude]; 

    } 
    else 
    { 
     reachable = NO; 
     [self getData]; 
     errorMsg = @"Because of unavailability of Network Realtime information wont be available."; 
     [self performSelectorOnMainThread:@selector(displayAlert) withObject:NULL waitUntilDone:YES]; 
    } 
    [reach startNotifier]; 
} 

請讓我知道我在這裏可能出錯的地方。 我通過將數據記錄到控制檯進行檢查。打印區域和國家，但經緯度爲空值。

Answer 1

如果您正在推送ForecastViewController，可能實施prepareForSegue:sender:是您的最佳選擇。

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender 
{ 

    if ([[segue identifier] isEqualToString:@"viewForecast"]){ 

    NSArray *seperate = [full componentsSeparatedByString:@", "]; 
    Area = seperate[0]; 
    Country = seperate[1];   
     [(ForecastViewController *) [segue destinationViewController] setArea:area]; 
[(ForecastViewController *) [segue destinationViewController] setCountry:country]; 
... 
... 
    } 
} 

Answer 2

我可以把那個緯度和經度作爲數字存儲在第一個控制器嗎？你確定在'ViewController'中'sendDetails.latitude'和'longitude'設置正確嗎？

Answer 3

我認爲你需要編輯兩個點首先在ForecastViewController.h設置

@property (Strong, nonatomic) NSString *Area; 
@property (Strong, nonatomic) NSString *Country; 
@property (Strong, nonatomic) NSString *latitude; 
@property (Strong, nonatomic) NSString *longitude; 

和ForecastViewController.m @synthsize它。 其次： -

- (IBAction)forecast:(UIButton *)sender 
    { 


    ForecastViewController *sendDetails = [self.storyboard instantiateViewControllerWithIdentifier:@"your ForecastViewController name in storyboard"]; 
    NSArray *seperate = [full componentsSeparatedByString:@", "]; 
    Area = seperate[0]; 
    Country = seperate[1]; 
    sendDetails.Area = Area; 
    sendDetails.Country = Country; 
    NSLog(@"%@%@",self.longitude,self.latitude); 
    NSString *lt = self.latitude; 
    NSString *ln = self.longitude; 
    sendDetails.longitude = lt; 
    sendDetails.latitude = ln; 
    [self.navigationController pushViewController:sendDetails animated:YES]; 
}