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我在我的应用程序中移动图像,这是正常工作。问题是,当用户回到该视图时,我想保留这些图像。目前,我使用的是字符串来保存图像中心:使用NSUserDefaults来存储图像坐标
NSString *centre = NSStringFromCGPoint(image.center);
我有一个NSUserDefault变量称为theCentre:
theCentre = [NSUserDefaults standardUserDefaults];
,我尝试使用保存:
[theCentre setObject:centre forKey:@"centre"];
当我输出日志时,我得到以下内容:
{280, 320}
这很棒。 在viewDidLoad中,我尝试了完全相同的日志,并且它正在返回(null)。我认为这意味着它没有妥善保存中心。我在这里错过了一些基本的东西,因为我在我的应用程序的其他地方使用了NSUserDefaults,并且它一直工作正常。提前谢谢了。
编辑:这是整个代码,试图帮助调试:)
-(void)getBounds
{
lowerBoundX = 250;
upperBoundX = 310;
lowerBoundY = 290;
upperBoundY = 350;
}
#pragma mark -
#pragma mark UIPanGestureRecognizer selector
- (void) dragGesture:(UIPanGestureRecognizer *) panGesture
{
[self getBounds];
CGPoint translation = [panGesture translationInView:self.view];
switch (panGesture.state) {
case UIGestureRecognizerStateBegan:{
originalCentre = dragImage.center;
}
break;
case UIGestureRecognizerStateChanged:{
dragImage.center = CGPointMake(dragImage.center.x + translation.x,
dragImage.center.y + translation.y);
}
break;
case UIGestureRecognizerStateEnded:{
if (((dragImage.center.x >= lowerBoundX) && (dragImage.center.y >= lowerBoundY) &&
(dragImage.center.x <= upperBoundX) && (dragImage.center.y <= upperBoundY))) {
dragImage.center = CGPointMake(280, 320);
[dragImage setUserInteractionEnabled:NO];
theCentre = [NSUserDefaults standardUserDefaults];
NSString *centre = NSStringFromCGPoint(dragImage.center);
[theCentre setObject:centre forKey:@"centre"];
NSLog(@"%@", [theCentre objectForKey:@"centre"]);
[theCentre synchronize];
break;
}
[UIView animateWithDuration:0.5
animations:^{
dragImage.center = originalCentre;
}
completion:^(BOOL finished){
}];
}
break;
default:
break;
}
[panGesture setTranslation:CGPointZero inView:self.view];
}
-(IBAction)clear{
[UIImageView animateWithDuration:0.5 animations:^{
dragImage.center = CGPointMake(100, 200);
}];
[dragImage setUserInteractionEnabled:YES];
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
NSLog(@"%@", [theCentre objectForKey:@"centre"]);
UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(dragGesture:)];
[dragImage addGestureRecognizer:panGesture];
[dragImage setUserInteractionEnabled:YES];
}
非常感谢你@Pawel,我实现了同步,但并没有改变任何东西。它也有意义!我将用整个代码编辑我的帖子,希望我能找到一个解决方案! –
您确定theCenter属性包含任何NSUserDefaults对象吗?看起来你正在dragGesture:方法中创建一个,但我不确定是否为viewDidLoad方法创建了一个。 – Pawel
我只将它作为一个变量,而不是一个属性;我错了吗? –