使uitextview以编程方式滚动

Question

我想使我的uitextview在应用程序启动时自动滚动。任何人都可以帮我一个详细的代码？我是iPhone SDK的新手。

Answer 1

.h文件中

@interface Credits : UIViewController 
{ 
    NSTimer *scrollingTimer; 

    IBOutlet UITextView *textView; 


} 
@property (nonatomic , retain) IBOutlet UITextView *textView; 

- (IBAction) buttonClicked ; 

- (void) autoscrollTimerFired; 

@end 

.m文件

- (void) viewDidLoad 
{  
    // it prints the initial position of text view 
    NSLog(@"%f %f",textView.contentSize.width , textView.contentSize.height); 

    if (scrollingTimer == nil) 
    { 
     // A timer that updates the content off set after some time so it can scroll 
     // you can change time interval according to your need (0.06) 
     // autoscrollTimerFired is the method that will be called after specified time interval. This method will change the content off set of text view 
     scrollingTimer = [NSTimer scheduledTimerWithTimeInterval:(0.06) 
         target:self selector:@selector(autoscrollTimerFired) userInfo:nil repeats:YES];   
    } 
} 

- (void) autoscrollTimerFired 
{ 
    CGPoint scrollPoint = self.textView.contentOffset; // initial and after update 
    NSLog(@"%.2f %.2f",scrollPoint.x,scrollPoint.y); 
    if (scrollPoint.y == 583) // to stop at specific position 
    { 
     [scrollingTimer invalidate]; 
     scrollingTimer = nil; 
    } 
    scrollPoint = CGPointMake(scrollPoint.x, scrollPoint.y + 1); // makes scroll 
    [self.textView setContentOffset:scrollPoint animated:NO]; 
    NSLog(@"%f %f",textView.contentSize.width , textView.contentSize.height); 

} 

希望它可以帮助你....

Answer 2

UITextView派生自UIScrollview，因此您可以使用-setContentOffset：animated：设置滚动位置。

假设你想以每秒10点的速度顺利滚动，你会做类似的事情。

- (void) scrollStepAnimated:(NSTimer *)timer { 
    CGFloat scrollingSpeed = 10.0; // 10 points per second 
    NSTimeInterval repeatInterval = [timer timeInterval]; // ideally, something like 1/30 or 1/10 for a smooth animation 

    CGPoint newContentOffset = CGPointMake(self.textView.contentOffset.x, self.textView.contentOffset.y + scrollingSpeed * repeatInterval); 
    [self.textView setContentOffset:newContentOffset animated:YES]; 
} 

当然，您必须设置计时器，并确保在视图消失时取消滚动等等。