关于不能重载imageView 的问题

有20个按钮，点击每个按钮后都应该根据对应的标签值加载数组图片，问题是只有第一个显示。

images=[[NSMutableArray alloc]init];
    [images insertObject:@"circle.png" atIndex:0];
    [images insertObject:@"cone.png" atIndex:1];
    [images insertObject:@"cube.png" atIndex:2];
    [images insertObject:@"cuboid.png" atIndex:3];
    [images insertObject:@"cylinder.png" atIndex:4];
    [images insertObject:@"ecplise.png" atIndex:5];
    [images insertObject:@"ellipsoid.png" atIndex:6];
    [images insertObject:@"frustrum of cone.png" atIndex:7];
    [images insertObject:@"kite.png" atIndex:8];
    [images insertObject:@"parallelepiped.png" atIndex:9];
    [images insertObject:@"parallelogram.png" atIndex:10];
    [images insertObject:@"polygon.png" atIndex:11];
    [images insertObject:@"rectangle.png" atIndex:12];
    [images insertObject:@"rectangula prizm.png" atIndex:13];
    [images insertObject:@"rhoumbus.png" atIndex:14];
    [images insertObject:@"sector.png" atIndex:15];
    [images insertObject:@"sphere.png" atIndex:16];
    [images insertObject:@"square.png" atIndex:17];
    [images insertObject:@"tapezoid.png" atIndex:18];
    [images insertObject:@"tourus.png" atIndex:19];
    [images insertObject:@"traingle.png" atIndex:20];
NSString * str=value2;
    NSLog(@"%@",str);
    //AppDelegate * delegate=(AppDelegate *)[[UIApplication sharedApplication]delegate];
    NSInteger myInt = [str intValue];
    NSString *  imagename=[images objectAtIndex:myInt];
    NSLog(@"%@",imagename);
    self.imgview.userInteractionEnabled=YES;
    [imgview setImage:[UIImage imageNamed:imagename]];
    [imgview setNeedsDisplay];
    [imgview reloadInputViews];

str包含按钮的标签值。