如何让UITextView一直显示滚动条

http://www.cocoachina.com/bbs/simple/?t64154.html

//头文件
#import <UIKit/UIKit.h>

@interface TextView : UIView<UITextViewDelegate>{
    UITextView *boxText;
}
- (id)initWithFrame:(CGRect)frame withContext:(NSString *)text;

@end


//实现文件
@implementation TextView

/**
 @method UITextView自定义重写封装
 @param frame 位置
 @param text 视图文本
 */
- (id)initWithFrame:(CGRect)frame withContext:(NSString *)text
{
    self = [super initWithFrame:frame];
    if (self) {
        boxText = [[UITextView alloc] initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];
        boxText.delegate = self;
        [boxText setText:text];
        [boxText setTextColor:[UIColor whiteColor]];
        [boxText setTextAlignment:UITextAlignmentLeft];
        [boxText setBackgroundColor:[UIColor clearColor]];
        [boxText setFont:[UIFont systemFontOfSize:15]];
        [boxText setEditable:YES];
        [self addSubview:boxText];
        [boxText release];
        
        [NSTimer scheduledTimerWithTimeInterval:0.4 target:self selector:@selector(run) userInfo:nil repeats:NO];
    }
    return self;
}

#pragma mark --视图移动后判断是否是UIImage，然后判断是否是竖滚动条设置让滚动条显示--
-(void)run{
    [boxText setContentOffset:CGPointMake(0, 10) animated:NO];
    for(UIView *img in [boxText subviews]){
        if ([img isKindOfClass:[UIImageView class]] && img.autoresizingMask == UIViewAutoresizingFlexibleLeftMargin){
            [img setAlpha:1];
        }
    }
}

#pragma mark --滚动视图结束移动后判断是否是UIImage，然后判断是否是竖滚动条设置让滚动条显示--
-(void)scrollViewDidEndDecelerating:(UIScrollView *)sc{
    for (UIView *img in [sc subviews]) {
        if ([img isKindOfClass:[UIImageView class]] && img.autoresizingMask == UIViewAutoresizingFlexibleLeftMargin){
            [img setAlpha:1];
        }
    }
}


#pragma mark --禁止UITextView的选择和编辑--
- (BOOL)textViewShouldBeginEditing:(UITextView *)textView
{
    return NO;
}

@end