contentsize、contentoffset和contentInset详解

下面我用怎么做一个书架的例子和大家说说contentsize、contentoffset 和contentInset的区别。

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NSString *path = nil;
UIImage *back = nil;
NSString *str = nil;
UIImage *aImage = nil;

path = [[NSBundle mainBundle] pathForResource:@"shujia" ofType:@"jpg"];
back = [UIImage imageWithContentsOfFile:path];//加载图片

_scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(96, 84,back.size.width,back.size.height)];
_scrollView.showsVerticalScrollIndicator = NO;      //将竖直方向的滚动条隐藏

//将shujia.jpg作为_scrollerView的背景
UIColor *color=[[UIColor alloc]initWithPatternImage:back];
[_scrollView setBackgroundColor:color];

_buttonList=[NSMutableArray arrayWithCapacity:9];
for(int i=0;i<9;i++)
{
    str=[NSString stringWithFormat:@"menubook%d",i+1];
    path = [[NSBundle mainBundle] pathForResource:str ofType:@"png"];
    aImage = [UIImage imageWithContentsOfFile:path];
    int x = (i%3)* (aImage.size.width+15);
    int y = (i/3)* (aImage.size.height+30);
    _whichPeople = [UIButton buttonWithType:UIButtonTypeCustom];
    _whichPeople.frame = CGRectMake(x+10,y+30,aImage.size.width,aImage.size.height);
    _whichPeople.tag = i;
    [_whichPeople setImage:aImage forState:UIControlStateNormal];//这个图片是在布点击时响应
    path = nil;
    aImage = nil;
    str = nil;

    str=[NSString stringWithFormat:@"menubook%d_1",i+1];
    path = [[NSBundle mainBundle] pathForResource:str ofType:@"png"];
    aImage = [UIImage imageWithContentsOfFile:path];
    [_whichPeople setImage:aImage forState:UIControlStateHighlighted];//图片在点击的时候响应
    [_whichPeople addTarget:self action:@selector(ButtonClick:) forControlEvents:UIControlEventTouchUpInside];
    [_scrollView addSubview:_whichPeople];
    [_buttonList addObject:_whichPeople];
    path = nil;
    aImage = nil;
    str = nil;

}

//控制可以滚动的区域
_scrollView.contentSize = CGSizeMake(480, 580);
//当前显示区域顶点相对于frame顶点的偏移量
_scrollView.contentOffset = CGPointMake(0, 0);
//scrollview的contentview的顶点相对于scrollview的位置
_scrollView.contentInset = UIEdgeInsetsMake(0 , 0, 0, 0);
[self.view addSubview:_scrollView];
contentSize是scrollview可以滚动的区域，比如frame = (0 ,0 ,320 ,480) contentSize = (320 ,960)，代表你的scrollview可以上下滚动，滚动区域为frame大小的两倍。
contentOffset是scrollview当前显示区域顶点相对于frame顶点的偏移量，比如上个例子你拉到最下面，contentoffset就是(0 ,480)，也就是y偏移了480
contentInset是scrollview的contentview的顶点相对于scrollview的位置，例如你的contentInset = (0 ,100)，那么你的contentview就是从scrollview的(0 ,100)开始显示

摘自 ComeOnTom的专栏

补充：移动开发 , IOS ,