坐标系转换

1、简单的两个view放到控制器的view里，其中blueView是redView的子控件

2、拖线到控制器里，打印各自的frame、转换坐标系后的frame

@interface ViewController ()

@property (weak, nonatomic) IBOutlet RedView *redView;

@property (weak, nonatomic) IBOutlet BlueView *blueView;

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

NSLog(@"self.redView：%@,self.blueView：%@",NSStringFromCGRect(self.redView.frame),NSStringFromCGRect(self.blueView.frame));

CGRect newRectRed = [self.redView convertRect:self.redView.bounds toView:[UIApplication sharedApplication].keyWindow];

CGRect newRectRed2 = [self.redView convertRect:self.redView.bounds toView:self.view];

CGRect newRectBlue = [self.blueView convertRect:self.blueView.bounds toView:[UIApplication sharedApplication].keyWindow];

CGRect newRectBlue2 = [self.blueView.superview convertRect:self.blueView.bounds toView:self.view];

NSLog(@"newRectRed：%@,newRectBlue：%@",NSStringFromCGRect(newRectRed),NSStringFromCGRect(newRectBlue));

NSLog(@"newRectRed2：%@,newRectBlue2：%@",NSStringFromCGRect(newRectRed2),NSStringFromCGRect(newRectBlue2));

}

3、结果如下

疑问：为什么转到keywindow后的坐标和转到控制器的view的坐标不同呢？