iOS开发---转换坐标系

 - (void)viewDidLoad
 {
     [super viewDidLoad];

     // 蓝色
     UIView *blue = [[UIView alloc] init];
     blue.backgroundColor = [UIColor blueColor];
     blue.frame = CGRectMake(, , , );
     [self.view addSubview:blue];
     self.blue = blue;

     // 红色
     UIView *red = [[UIView alloc] init];
     red.backgroundColor = [UIColor redColor];
     red.frame = CGRectMake(, , , );
     [blue addSubview:red];
     self.red = red;

     // 黄色
     UIView *yellow = [[UIView alloc] init];
     yellow.backgroundColor = [UIColor yellowColor];
     yellow.frame = CGRectMake(, , , );
     [red addSubview:yellow];
     self.yellow = yellow;

     // 紫色
     UIView *purple = [[UIView alloc] init];
     purple.backgroundColor = [UIColor purpleColor];
     purple.frame = CGRectMake(, , , );
     [self.view addSubview:purple];
     self.purple = purple;
 }

 - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
 {
 //    NSLog(@"%@", NSStringFromCGRect(self.yellow.bounds));
 //    NSLog(@"%@", NSStringFromCGRect(self.yellow.frame));

     // 计算self.yellow在self.blue中的位置和尺寸
 //    CGRect newRect = [self.yellow convertRect:self.yellow.bounds toView:self.blue];

     // 计算self.yellow在self.purple中的位置和尺寸
 //    CGRect newRect = [self.yellow.superview convertRect:self.yellow.frame toView:self.purple];

     // 计算self.red在self.yellow中的位置和尺寸
     //    CGRect newRect = [self.red convertRect:self.red.bounds toView:self.yellow];
     // 计算self.red在self.yellow中的位置和尺寸
 //    CGRect newRect = [self.yellow convertRect:self.red.bounds fromView:self.red];

     // 计算self.red在屏幕中的位置和尺寸(nil代表屏幕)
     CGRect newRect = [self.red convertRect:self.red.bounds toView:nil];
     NSLog(@"%@", NSStringFromCGRect(newRect));
 }