视图间坐标转换

- (void)viewDidLoad
{
    [super viewDidLoad];
	
    UIView *view1 = [[UIView alloc] initWithFrame:CGRectMake(10.0f, 100.0f, 300.0f, 100.0f)];
    view1.backgroundColor = [UIColor blackColor];
    UIView *view2 = [[UIView alloc] initWithFrame:CGRectMake(30.0f, 20.0f, 50.0f, 50.0f)];
    view2.backgroundColor = [UIColor whiteColor];
    [view1 addSubview:view2];
    [self.view addSubview:view1];
    
    // converRect: toView
    CGRect rect1 = [view1 convertRect:CGRectMake(30.0f, 20.0f, 50.0f, 50.0f) toView:view2]; // 将view1中的frame转换成在view2中的frame
    CGPoint point1 = [view1 convertPoint:CGPointMake(30.0f, 20.0f) toView:view2];           // 将view1中的point转换成在view2中的point
    NSLog(@"rect1:(%f,%f,%f,%f)",rect1.origin.x,rect1.origin.y,rect1.size.width,rect1.size.height);
    NSLog(@"point1:(%f,%f)",point1.x,point1.y);
    
    // converRect: fromView
    CGRect rect2 = [view2 convertRect:CGRectMake(30.0f, 20.0f, 50.0f, 50.0f) fromView:view1]; // 将view1中的frame转换成在view2中的frame(同上)
    CGPoint point2 = [view2 convertPoint:CGPointMake(30.0f, 20.0f) fromView:view1];           // 将view1中的point转换成在view2中的point(同上)
    NSLog(@"rect2:(%f,%f,%f,%f)",rect2.origin.x,rect2.origin.y,rect2.size.width,rect2.size.height);
    NSLog(@"point2:(%f,%f)",point2.x,point2.y);
    
    // 特殊
    CGRect rect = [view1 convertRect:CGRectMake(30.0f, 20.0f, 50.0f, 50.0f) toView:nil];     // 这view1中的frame转换成基于窗口坐标的frame
    NSLog(@"rect:(%f,%f,%f,%f)",rect.origin.x,rect.origin.y,rect.size.width,rect.size.height);
    
    [view1 release];
    [view2 release];
}

输出结果:

结论:

1、A convert xxx to B / B convert xxx from A 将视图A中的坐标系统转换成视图B中的坐标系统；

2、A convert xxx to B，B为nil时将视图A中的坐标系统转换成窗口的坐标系统。