一个诡异的问题

@interface UIView (Zoom)
-(void)viewZoomMaxBounds:(CGRect) maxBounds minBounds:(CGRect) minBounds finallyBounds:(CGRect) finallyBounds;
@end
#import "UIView+Zoom.h"
@implementation UIView (Zoom)
-(void)viewZoomMaxBounds:(CGRect)maxBounds minBounds:(CGRect) minBounds finallyBounds:(CGRect)finallyBounds
{
    [UIView animateWithDuration:0.3f animations:^{
        self.bounds=maxBounds;
    } completion:^(BOOL finished){
        [UIView animateWithDuration:0.1f animations:^{
            self.bounds=minBounds;
        } completion:^(BOOL finished){
            [UIView animateWithDuration:0.05f animations:^{
                self.bounds=finallyBounds;
            }completion:^(BOOL finished){
                [[NSNotificationCenter defaultCenter] postNotificationName:@"finished" object:nil];
            }];        }];
    }];
}
@end
这是我写的一个category    增加uiview一个动画功能
    registerView=[[RegisterView alloc] initWithFrame:CGRectMake(160, 197, 0, 0)];
NSLog(@"1:%i",registerView.retainCount);
registerView.delegate=self;
registerView.backgroundColor=[UIColor blackColor];
    [self.view addSubview:registerView];
NSLog(@"2:%i",registerView.retainCount);
    [registerView viewZoomMaxBounds:CGRectMake(0, 0, 320, 394) minBounds:CGRectMake(0, 0, 290, 360) finallyBounds:CGRectMake(0, 0, 300, 380)];
NSLog(@"3:%i",registerView.retainCount);
    [registerView release];
NSLog(@"4:%i",registerView.retainCount);
    [super viewDidAppear:animated];
这个是代码中的调用   先是创建一个view  
可是调用了红色代码以后retaincount加一了，不知道为什么？  求高手指点
[registerView viewZoomMaxBounds:CGRectMake(0, 0, 320, 394) minBounds:CGRectMake(0, 0, 290, 360) finallyBounds:CGRectMake(0, 0, 300, 380)];