iOS UIScrollView的代理的使用及缩放时代理监听的几个方法

必须至少有三个步骤：

一，实现协议

二，建立关系

三，设置缩放的范围

具体见代码：

#import "ViewController.h"

@interface ViewController () <UIScrollViewDelegate> //一定要先遵守这个协议
@property (weak, nonatomic) IBOutlet UIScrollView *ScrollView;
@property (weak, nonatomic) IBOutlet UIImageView *minionPic;

@end

@implementation ViewController

//滚动过程中，一直会调用该方法
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    //NSLog(@"scrollViewDidScroll");
}

//开始滚动时调用该方法，在拖拽一次，该方法只调用一次且为最初开始时调用一次
-(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
    //NSLog(@"scrollViewWillBeginDragging");
}

//当用户开始缩放动作时代理要触发的事件
- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view
{
    NSLog(@"scrollViewWillBeginZooming");
}

//当用户缩放时，要设置绽放哪个View？
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    return self.minionPic;
}

- (void)viewDidLoad {

    [super viewDidLoad];

    //设置ScrollView的内容大小contentSize
    self.ScrollView.contentSize= self.minionPic.frame.size;
    //绑定代理，建立ScrollView与代理的关系
    self.ScrollView.delegate = self;

    //设置缩放的范围
    self.ScrollView.minimumZoomScale = 0.2;
    self.ScrollView.maximumZoomScale =2.0;

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

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end