坐标转换convertRect,从此不再迷糊

坐标转换在开发中经常使用，有时容易搞混，最近正好搞了一次，记录一下...

- (CGPoint)convertPoint:(CGPoint)point toView:(nullable UIView *)view;
- (CGPoint)convertPoint:(CGPoint)point fromView:(nullable UIView *)view;
- (CGRect)convertRect:(CGRect)rect toView:(nullable UIView *)view;
- (CGRect)convertRect:(CGRect)rect fromView:(nullable UIView *)view;

//创建一个tabl
mTabl = [[UITableView alloc] initWithFrame:CGRectMake(0, 200, CGRectGetWidth(self.view.frame), CGRectGetHeight(self.view.frame)-64-200) style:UITableViewStylePlain];

-(CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{
    return 105;//cell的高度
}
//我们在cell上加一个控件
 if (![cell.contentView viewWithTag:1000]){
        UIView *subCellView = [[UIView alloc] initWithFrame:CGRectMake(100, 10, 200, 20)];
        subCellView.backgroundColor = [UIColor orangeColor];
        subCellView.tag = 1000;
        [cell.contentView addSubview:subCellView];
    }

点击第二个cell

UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
    UIView *subCellView = [cell.contentView viewWithTag:1000];
    CGRect subCellRect = [subCellView.superview convertRect:subCellView.frame toView:self.view];
    
    NSLog(@"%@ --- %@",NSStringFromCGRect(subCellView.frame),NSStringFromCGRect(subCellRect));

    subCellRect = [self.view convertRect:subCellView.frame fromView:subCellView.superview];
    
    NSLog(@"%@ --- %@",NSStringFromCGRect(subCellView.frame),NSStringFromCGRect(subCellRect));

2018-05-21 09:49:09.663619+0800 TestPosition[98777:2942237] {{100, 10}, {200, 20}} --- {{100, 315}, {200, 20}}
2018-05-21 09:49:09.663792+0800 TestPosition[98777:2942237] {{100, 10}, {200, 20}} --- {{100, 315}, {200, 20}}

我们来计算一下subview（tag为1000的view）相对于self.view的高度
200（tabl的Y） + 105（第一个cell的高度） + 10（相对于父视图的Y） = 315 （Y）
和输出的结果正好一致.

所以，使用 规则如下：

获取相对于self.view的坐标位置
 [subCellView.superview convertRect:subCellView.frame toView:self.view]
[self.view convertRect:subCellView.frame fromView:subCellView.superview]