I have a circle image with radius 50, and now I want to put the circyle's center the same as my View's center like this:

```
- (void)drawRect:(CGRect)rect {
    UIImage *arrow = [UIImage imageWithPDFNamed:@"circle" atSize:CGSizeMake(50, 50)];
    [arrow drawAtPoint:self.center];
}

```

But drawAtPoint is not drawing at the center.
I want to know how to locate the center of the image? so I can draw it?