拖動條和進度條非常相似

只是進度條采用顏色填充來標明進度完成的程度，拖動條則通過滑塊的位置來標識數值

UIImage* minImage=[[UIImage imageNamed:@"images/heart.gif"]

resizableImageWithCapInsets:UIEdgeInsetsZero resizingMode:UIImageResizingModeTile];

UIImage* trackImage=[[UIImage imageNamed:@"images/ic_launcher.png"]

resizableImageWithCapInsets:UIEdgeInsetsZero

resizingMode:UIImageResizingModeTile];

UIImage* maxImage=[[UIImage imageNamed:@"images/grow.gif"]

resizableImageWithCapInsets:UIEdgeInsetsZero resizingMode:UIImageResizingModeTile];

UIImage* imageIV=[UIImage imageNamed:@"images/lijiang.jpg"];

self.iv=[[UIImageView alloc]initWithFrame:CGRectMake(0, 40, 450, 300)];

self.iv.image=imageIV;

[self.view addSubview:self.iv];

//@"images/ic_launcher.png"

self.slider=[[UISlider alloc]initWithFrame:CGRectMake(0, 300, 450, 40)];

[self.slider setMinimumTrackImage:minImage forState:UIControlStateNormal];

[self.slider setMaximumTrackImage:maxImage forState:UIControlStateNormal];

[self.slider setThumbImage:trackImage forState:UIControlStateNormal];

self.slider.value=0.0;

[self.slider addTarget:self action:@selector(change:) forControlEvents:UIControlEventValueChanged];

[self.view addSubview:self.slider];

// Do any additional setup after loaing the view, typically from a nib.

}

-(void)change:(UISlider*)sender{

//

[self.iv setAlpha:sender.value];

}