IOS自学—浅谈ScrollView各个属性及代理的实现

一 ScrollView的常用属性及介绍：

@property(nonatomic)CGPoint contentOffset;相对于起始位置的偏移量x和y，默认以左上角为原点是（0，0）

// default CGPointZero  

@property(nonatomic)CGSize contentSize;  定义滚动视图内容的尺寸大小

// default CGSizeZero   

@property(nonatomic)UIEdgeInsets  contentInset;设置滚动边距

// default UIEdgeInsetsZero. add additional scroll area around content

@property(nonatomic,assign)id<UIScrollViewDelegate> delegate;代理

// default nil. weak reference

@property(nonatomic,getter=isDirectionalLockEnabled)BOOLdirectionalLockEnabled;指定ScrollView是否只能在一个方向上滚动，默认是NO

// default NO. if YES, try to lock vertical or horizontal scrolling while dragging

@property(nonatomic)BOOL bounces;内容遇到边框是否反弹，默认是YES

// default YES. if YES, bounces past edge of content and back again

@property(nonatomic)BOOLalwaysBounceVertical;垂直方向内容遇到边框是否返回，默认是YES

// default NO. if YES and bounces is YES, even if content is smaller than bounds, allow drag vertically

@property(nonatomic)BOOL alwaysBounceHorizontal;水平方向内容遇到边框是否返回，默认是YES

// default NO. if YES and bounces is YES, even if content is smaller than bounds, allow drag horizontally

@property(nonatomic,getter=isPagingEnabled)BOOL pagingEnabled;是否分页，默认是NO

// default NO. if YES, stop on multiples of view bounds

@property(nonatomic,getter=isScrollEnabled)BOOL scrollEnabled;是否允许滚动，默认是YES

// default YES. turn off any dragging temporarily

@property(nonatomic)BOOLshowsHorizontalScrollIndicator;是否显示水平方向滚动条，默认是YES

// default YES. show indicator while we are tracking. fades out after tracking

@property(nonatomic)BOOLshowsVerticalScrollIndicator;是否显示垂直方向滚动条，默认是YES

// default YES. show indicator while we are tracking. fades out after tracking

@property(nonatomic)UIEdgeInsets  scrollIndicatorInsets;滚动条在视图中的位置，若未设置偏移，默认是在视图中央

// default is UIEdgeInsetsZero. adjust indicators inside of insets

@property(nonatomic UIScrollViewIndicatorStyle indicatorStyle;滚动条的样式，默认是UIScrollViewIndicatorStyleDefault

// default is UIScrollViewIndicatorStyleDefault

@property(nonatomic)CGFloat decelerationRateNS_AVAILABLE_IOS(3_0);滚动速率

部分代码演示：

#import "ViewController.h"

@interface ViewController ()<UIScrollViewDelegate>

{

    UIScrollView *scv;

    UIImageView *imgView;

}

@end

@implementation ViewController

- (void)viewDidLoad {

    [super viewDidLoad];

    scv = [[UIScrollView alloc]initWithFrame:[[UIScreen mainScreen] bounds]];

    self.view = scv;

    scv.delegate = self;

    imgView = [[UIImageView alloc]init];

    imgView.image = [UIImage imageNamed:@"2_5"];

    [scv addSubview:imgView];

// 让视图根据图像自己调整大小

    [imgView sizeToFit];

// 定义滚动视图内容的尺寸大小

    scv.contentSize =  imgView.image.size;

// 设置滚动边距

    scv.contentInset = UIEdgeInsetsMake(100, 100, 100, 100);

// 设置偏移位置

    scv.contentOffset = CGPointMake(0, 0);

// 隐藏水平滚动标示

//  scv.showsHorizontalScrollIndicator = NO;

// 隐藏垂直滚动标示

//  scv.showsVerticalScrollIndicator = NO;

    scv.directionalLockEnabled = YES;

// NO时滚动时不会超出可见范围

    scv.bounces = YES;

    scv.pagingEnabled = YES;

// 滚动条在视图中的位置

    scv.scrollIndicatorInsets = UIEdgeInsetsMake(0 , 0, 0, 0);

// 设置最大最小缩放比例

    scv.minimumZoomScale = 0.5;

    scv.maximumZoomScale = 2.0;

}

二 ScrollView的常用代理方法：

// scrollView已经滑动

- (void)scrollViewDidScroll:(UIScrollView *)scrollView

{

    NSLog(@"－－－－－－－－scrollViewDidScroll方法被调用了－－－－－－－－");

    NSLog(@"ContentOffset  x is  %f,y is %f",scv.contentOffset.x,scv.contentOffset.y);

}

// scrollView将要开始拖动

- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView

{

    NSLog(@"－－－－－－－－scrollViewWillBeginDragging方法被调用了－－－－－－－－");

}

// scrollView将要停止拖动

- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset NS_AVAILABLE_IOS(5_0)

{

    NSLog(@"－－－－－－－－scrollViewWillEndDragging方法被调用了－－－－－－－－");

}

// scrollView停止拖动

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate

{

    NSLog(@"－－－－－－－－scrollViewDidEndDragging方法被调用了－－－－－－－－");

}

// scrollView将要开始减速

- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView

{

    NSLog(@"－－－－－－－－scrollViewWillBeginDecelerating方法被调用了－－－－－－－－");

}

// scrollView停止减速

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView

{

    NSLog(@"－－－－－－－－scrollViewDidEndDecelerating方法被调用了－－－－－－－－");

}

// 滚动动画停止时执行,代码改变时触发,也就是setContentOffset改变时

- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView

{

    NSLog(@"－－－－－－－－scrollViewDidEndScrollingAnimation方法被调用了－－－－－－－－");

}

// 返回一个放大或者缩小的视图

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView

{

    return imgView;

}

// 开始放大或者缩小

- (void)scrollViewWillBeginZooming:(UIScrollView *)scrollView withView:(UIView *)view NS_AVAILABLE_IOS(3_2)

{

    NSLog(@"－－－－－－－－scrollViewWillBeginZooming方法被调用了－－－－－－－－");

}

// 缩放进行中

- (void)scrollViewDidZoom:(UIScrollView *)scrollView NS_AVAILABLE_IOS(3_2)

{

    NSLog(@"－－－－－－－－scrollViewDidZoom方法被调用了－－－－－－－－");

}

// 缩放结束时

- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale

{

    NSLog(@"－－－－－－－－scrollViewDidEndZooming方法被调用了－－－－－－－－");

}

// 是否支持滑动至顶部

- (BOOL)scrollViewShouldScrollToTop:(UIScrollView *)scrollView

{

    NSLog(@"－－－－－－－－scrollViewShouldScrollToTop方法被调用了－－－－－－－－");

    return YES;

}

// 滑动到顶部时调用该方法

- (void)scrollViewDidScrollToTop:(UIScrollView *)scrollView

{

    NSLog(@"－－－－－－－－scrollViewDidScrollToTop方法被调用了－－－－－－－－");

}