我对自定义视图和自动布局有疑问。为简单起见，我将使用两个 UILabel，第一个应该在设备旋转时更改其背景颜色。问题是它不这样做！有什么提示吗？谢谢！尼古拉
- (id)init
{
self = [super init];
if (self) {
//Add the subviews to the mainView
[self.view addSubview:self.label1];
[self.view addSubview:self.label2];
//Autolayout
//Create the views dictionary
NSDictionary *viewsDictionary = @{@"header":self.label1,
@"table": self.label2};
//Create the constraints using the visual language format
[self.view addConstraints:[NSLayoutConstraint
constraintsWithVisualFormat: @"H:|[header]|"
options:0
metrics:nil
views:viewsDictionary]];
[self.view addConstraints:[NSLayoutConstraint
constraintsWithVisualFormat: @"H:|[table]|"
options:0
metrics:nil
views:viewsDictionary]];
[self.view addConstraints:[NSLayoutConstraint
constraintsWithVisualFormat:@"V:|[header(==50)][table]|"
options:0
metrics:nil
views:viewsDictionary]];
}
return self;
}
-(UIView*) label1
{
_label1 = [UILabel alloc] init];
if (UIInterfaceOrientationIsPortrait(self.interfaceOrientation)){
_label1.backgroundColor = [UIColor redColor];
}else{
_label1.backgroundColor = [UIColor greenColor];
}
_label1.translatesAutoresizingMaskIntoConstraints=NO;
return _label1;
}
-(UIView*) label2
{
_label2 = [UILabel alloc] init];
_label2.backgroundColor = [UIColor yellowColor];
_label2.translatesAutoresizingMaskIntoConstraints=NO;
_return label2;
}
-(BOOL) shouldAutorotate
{
return YES;
}
-(NSUInteger) supportedInterfaceOrientations
{
if([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad){
//I am on a pad
return UIInterfaceOrientationMaskAll;
} else {
//I am on a Phone
return UIInterfaceOrientationMaskAllButUpsideDown;
}
}
-(void) willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
//I expect the label1 to change its background color
[self.view setNeedDisplay];
}