iOS开发Navigation 导航栏渐变

来源：互联网发布：洗相片软件编辑：程序博客网时间：2024/05/19 15:43

方法有多种，无外乎监听scrollView变化，通过代理方法实现。
下面是比较简单直观的方法：

-(void)viewWillAppear:(BOOL)animated{    [superviewWillAppear:animated];     if (self.navigationController) {        [self.navigationControllersetNavigationBarHidden:YES animated:animated];    }}-(void)viewDidDisappear:(BOOL)animated{        [superviewDidDisappear:animated];      if (self.navigationController) {        [self.navigationControllersetNavigationBarHidden:NOanimated:NO];    }}- (void)scrollViewDidScroll:(UIScrollView *)scrollView{    if (scrollView.contentOffset.y < 0) {        [selfshowView:_naviViewhidden:YES];        [selfsetStatusBarStyle:UIStatusBarStyleDefault];       }else if(scrollView.contentOffset.y > 50) {        [selfshowView:_naviViewhidden:NO];        CGFloat alpha = MIN(1, 1 - ((50 + 64 - scrollView.contentOffset.y) / 64));        [_naviViewsetBackgroundColor:[[UIColorwhiteColor] colorWithAlphaComponent:alpha]];    }else{        [selfshowView:_naviViewhidden:NO];        [_naviViewsetBackgroundColor:[[UIColorwhiteColor] colorWithAlphaComponent:0.0f]];    }}-(void)showView:(UIView *)view hidden:(BOOL)hidden{              CATransition *animation = [CATransitionanimation];                animation.type = kCATransitionFade;            animation.duration = 0.4;            [view.layeraddAnimation:animation forKey:nil];            view.hidden = hidden;}//根据数组随机生成一个长度为3内容不重复的数组-(NSArray*)createRandomArray:(NSMutableArray*)mutableArray{    if (mutableArray.count < 4) {        return mutableArray;    }else{        NSMutableArray *startArray = [NSMutableArray array];        NSMutableArray *resultArray=[[NSMutableArray alloc] initWithCapacity:0];        for (NSInteger i = 0; i < mutableArray.count; i++) {            [startArray addObject:[NSString stringWithFormat:@"%ld",i]];        }        for (int i = 0; i<3; i++) {            int t = arc4random()%startArray.count;            resultArray[i] = startArray[t];            startArray[t] = [startArray lastObject];            [startArray removeLastObject];        }        NSInteger i = [resultArray[0] integerValue];        NSInteger j = [resultArray[1] integerValue];        NSInteger k = [resultArray[2] integerValue];        return @[mutableArray[i], mutableArray[j], mutableArray[k]];    }}

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