UItextview滚动条一直显示

希望帮助后来开发者节省时间更多投入到其他逻辑上
UITextView继承自 UIScrollView，所以通过定时器调用 flashScrollIndicators 方法 即可一直显示滚动条。

@interface GYTextView : UITextView
@property(nonatomic) CGFloat verticalScrollBarH;
@property(nonatomic,strong)NSTimer *timer;
@end

import "GYTextView.h"

@implementation GYTextView

-(instancetype)initWithFrame:(CGRect)frame{
if (self=[super initWithFrame:frame]) {
self.tag = 836913;
if (@available(iOS 10.0, *)) {
self.timer=[NSTimer scheduledTimerWithTimeInterval:0.4 repeats:YES block:^(NSTimer * _Nonnull timer) {
// [self flashScrollIndicators];

            [CATransaction begin];
            [CATransaction setDisableActions:true];
            [self flashScrollIndicators];
            [CATransaction commit];
        }];
    } else {
        // Fallback on earlier versions
    }
    
    [self.timer fire];
}
return self;

}

-(instancetype)init{
if (self=[super init]) {

    self.tag = 836913;
    
    if (@available(iOS 10.0, *)) {
        self.timer=[NSTimer scheduledTimerWithTimeInterval:0.4 repeats:YES block:^(NSTimer * _Nonnull timer) {
            
            [CATransaction begin];
            [CATransaction setDisableActions:true];
            [self flashScrollIndicators];
            [CATransaction commit];

// [self flashScrollIndicators];
}];
} else {
// Fallback on earlier versions
}

    [self.timer fire];
    
}
return self;

}

-(BOOL)canPerformAction:(SEL)action withSender:(id)sender {
UIMenuController *menuController = [UIMenuController sharedMenuController];
if (menuController) {
[UIMenuController sharedMenuController].menuVisible = NO;
}
return NO;
}

-(void)flashScrollIndicators{
[super flashScrollIndicators];

// CATransaction *transition=[[CATransaction alloc] init];
// [transition begin];

if (self.scrollEnabled) {
       [self showScrollBar];
   }

}

-(void)showScrollBar{
NSLog(@"textTimer11111111");
for(UIView *img in [self subviews]){

    if ([img isKindOfClass:[UIImageView class]] && img.autoresizingMask == UIViewAutoresizingFlexibleLeftMargin){
        UIImageView *scollBar = (UIImageView *)img;
        CGRect frame = scollBar.frame;
        frame.origin.y = 0;
        [scollBar setFrame:frame];
    //    NSLog(@"frameY====%f====frameX====%f====frameWith==%fandframeHeight==%f",frame.origin.y,frame.origin.x,frame.size.width,frame.size.height);
        [scollBar setAlpha:1];
    }
}

}

-(void)didMoveToWindow{
[super didMoveToWindow];
[self flashScrollIndicators];
}

@end