iOS中scrollview自动滚动的实现

原问题是，我要展现给用户的内容放在scrollview中，让内容从上到底自动滚动，我最开始用的是DDAutoscrollview，但是无法实现。

一种解决方案见下边，更多解决方案见：http://ask.csdn.net/questions/374

.h文件

@interface Interface1 : UIViewController {

IBOutlet UIScrollView *scroller;
IBOutlet UILabel *warnung;

}

@property (nonatomic, retain) IBOutlet UIScrollView* scrollView;

.m文件

- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
CGPoint bottomOffset = CGPointMake(self.scrollView.contentOffset.x, self.scrollView.contentSize.height - self.scrollView.bounds.size.height);
[self.scrollView setContentOffset:bottomOffset animated:NO];

CGPoint newOffset = self.scrollView.contentOffset;
newOffset.y = 0;
[self.scrollView setContentOffset:newOffset animated:YES];
}

- (void)viewDidLoad
{

[scroller setScrollEnabled:YES];
[scroller setContentSize:CGSizeMake(320, 420)];

[super viewDidLoad];
}

使用

setContentOffset:animated:

UIScrollView *scrollView = ...;
CGPoint newOffset = scrollView.contentOffset;
newOffset.y = 0;
[scrollView setContentOffset:newOffset animated:YES];

如果需要开场动画的效果，在scrollView的viewcontroller实现

- (void)viewDidLoad
{
[super viewDidLoad];

// ...

CGPoint bottomOffset = CGPointMake(self.scrollView.contentOffset.x, self.scrollView.contentSize.height - self.scrollView.bounds.size.height);
[self.scrollView setContentOffset:bottomOffset animated:NO];
}
- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];

CGPoint newOffset = self.scrollView.contentOffset;
newOffset.y = 0;
[self.scrollView setContentOffset:newOffset animated:YES];
}

移动的慢点，用timer实现：

- (void)viewDidLoad
{
[super viewDidLoad];

// ...

CGPoint bottomOffset = CGPointMake(self.scrollView.contentOffset.x, self.scrollView.contentSize.height - self.scrollView.bounds.size.height);
[self.scrollView setContentOffset:bottomOffset animated:NO];
}

- (void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];

CGPoint bottomOffset = CGPointMake(self.scrollView.contentOffset.x, self.scrollView.contentSize.height - self.scrollView.bounds.size.height);

//设置延迟时间
float scrollDurationInSeconds = 4.0;

//计算timer间隔

float totalScrollAmount = bottomOffset.y;
float timerInterval = scrollDurationInSeconds / totalScrollAmount;

[NSTimer scheduledTimerWithTimeInterval:timerInterval target:self selector:@selector(scrollScrollView:) userInfo:nil repeats:YES];
}

- (void)scrollScrollView:(NSTimer *)timer
{
CGPoint newScrollViewContentOffset = self.scrollView.contentOffset;

//向上移动 1px
newScrollViewContentOffset.y -= 1;

newScrollViewContentOffset.y = MAX(0, newScrollViewContentOffset.y);

//如果到顶了，timer中止
if (newScrollViewContentOffset.y == 0) {
[timer invalidate];
}

//最后设置scollView's contentOffset
self.scrollView.contentOffset = newScrollViewContentOffset;
}