iOS开发UIScrollView一直显示滚动条,滚动条的一些属性

来源：互联网发布：tv破解版软件编辑：程序博客网时间：2024/06/06 10:31

一.UIScrollView显示或者隐藏滚动条, 默认有两个属性

@property(nonatomic)         BOOL                         showsHorizontalScrollIndicator; // default YES. show indicator while we are tracking. fades out after tracking

@property(nonatomic)         BOOL                         showsVerticalScrollIndicator;   // default YES. show indicator while we are tracking. fades out after tracking

这两个属性默认是YES, 显示水平和垂直滚动条, 只有当我们滚动的时候显示,当我们不滚动时,慢慢淡出

二.UIScrollView滚动条的样式, 默认有三个样式

@property(nonatomic)         UIScrollViewIndicatorStyle   indicatorStyle;                 // default is UIScrollViewIndicatorStyleDefault

typedef NS_ENUM(NSInteger, UIScrollViewIndicatorStyle) {    UIScrollViewIndicatorStyleDefault,     // black with white border. good against any background    UIScrollViewIndicatorStyleBlack,       // black only. smaller. good against a white background    UIScrollViewIndicatorStyleWhite        // white only. smaller. good against a black background};

这个属性默认是UIScrollViewIndicatorStyleDefault, 第二个属性UIScrollViewIndicatorStyleBlack 滚动条是黑色, 第三个属性UIScrollViewIndicatorStyleWhite 滚动条是白色

三.UIScrollView滚动条的偏移量

@property(nonatomic)         UIEdgeInsets                 scrollIndicatorInsets;          // default is UIEdgeInsetsZero. adjust indicators inside of insets

这个属性默认是UIEdgeInsetsZero, 我们可以自己设置偏移量

四.UIScrollView滚动条一直显示

1.我们知道滚动条是一个UIImageView, 滚动条隐藏是因为设置了alpha属性为0, 所有我们写一个UIImageView的分类

#define noDisableVerticalScrollTag 836913#define noDisableHorizontalScrollTag 836914@implementation UIImageView (WLScrollView)- (void)setAlpha:(CGFloat)alpha {if (self.superview.tag == noDisableVerticalScrollTag) {    if (alpha == 0 && self.autoresizingMask == UIViewAutoresizingFlexibleLeftMargin) {        if (self.frame.size.width < 10 && self.frame.size.height > self.frame.size.width) {            UIScrollView *sc = (UIScrollView*)self.superview;            if (sc.frame.size.height < sc.contentSize.height) {                return;            }        }    }}if (self.superview.tag == noDisableHorizontalScrollTag) {    if (alpha == 0 && self.autoresizingMask == UIViewAutoresizingFlexibleTopMargin) {        if (self.frame.size.height < 10 && self.frame.size.height < self.frame.size.width) {            UIScrollView *sc = (UIScrollView*)self.superview;            if (sc.frame.size.width < sc.contentSize.width) {                return;            }        }    }}[super setAlpha:alpha];}@end

2.写完分类之后, 我们在初始化UIScrollView的时候设置UIScrollView的tag为836913

3.要在UIScrollView数据绑定之后, 调用以下方法

- (void)flashScrollIndicators;             // displays the scroll indicators for a short time. This should be done whenever you bring the scroll view to front.

即调用以下方法

[scrollView reloadData];[scrollView flashScrollIndicators];

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