xcode 如何从一个视图控制器访问另一个视图控制器的变量值？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/2548910/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How do I access variable values from one view controller in another?
提问by Thomas
I have an integer variable (time) in one view controller whose value I need in another view controller. Here's the code:
我在一个视图控制器中有一个整数变量 ( time)，我需要在另一个视图控制器中使用它的值。这是代码：
MediaMeterViewController
媒体仪表视图控制器
// TRP - On Touch Down event, start the timer
-(IBAction) startTimer
{
time = 0;
// TRP - Start a timer
timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(updateTimer) userInfo:nil repeats:YES];
[timer retain]; // TRP - Retain timer so it is not accidentally deallocated
}
// TRP - Method to update the timer display
-(void)updateTimer
{
time++;
// NSLog(@"Seconds: %i ", time);
if (NUM_SECONDS == time)
[timer invalidate];
}
// TRP - On Touch Up Inside event, stop the timer, decide stress level, display results
-(IBAction) btn_MediaMeterResults
{
[timer invalidate];
NSLog(@"Seconds: %i ", time);
ResultsViewController *resultsView = [[ResultsViewController alloc] initWithNibName:@"ResultsViewController" bundle:nil];
[self.view addSubview:resultsView.view];
}
And in ResultsViewController, I want to process timebased on its value
在 ResultsViewController 中，我想根据其值处理时间
ResultsViewController
结果视图控制器
- (void)viewDidLoad
{
if(time < 3)
{// Do something}
else if ((time > 3) && (time < 6))
{// Do something else}
//etc...
[super viewDidLoad];
}
I'm kind of unclear on when @property and @synthesize is necessary. Is that the case in this situation? Any help would be greatly appreciated.
我不太清楚何时需要 @property 和 @synthesize。在这种情况下是这样吗？任何帮助将不胜感激。
Thanks! Thomas
谢谢！托马斯
回答by indragie
Declare timeas a property in MediaMeterViewController:
在 中声明time为属性MediaMeterViewController：
@property (nonatomic) NSInteger time;
Whenever you need to access an instance variable in another object, you should have the instance variable declared as a property, and when you declare a property you must always use @synthesize(to synthesize the getter and setter for that property).
每当您需要访问另一个对象中的实例变量时，您应该将该实例变量声明为一个属性，并且当您声明一个属性时，您必须始终使用@synthesize（以合成该属性的 getter 和 setter）。
Also take note that when setting timein MediaMeterViewControlleryou must always use self.timeinstead of time. For example, time = 0;should be self.time = 0;.
另请注意，在设置time时MediaMeterViewController必须始终使用self.time而不是time。例如，time = 0;应该是self.time = 0;。
To access timefrom your ResultsViewController, you would do something like this:
要从time您的访问ResultsViewController，您可以执行以下操作：
- (void)viewDidLoad
{
[super viewDidLoad];
if (mmvc.time < 3)
{
// Do something
}
else if ((mmvc.time > 3) && (mmvc.time < 6))
{
// Do something else
}
// etc...
}
Where mmvcis a reference to your MediaMeterViewControllerobject. Hope this helps.
哪里mmvc是对您的MediaMeterViewController对象的引用。希望这可以帮助。
