【代码笔记】点击加号增加书架，点击减号减少书架

一，效果图。

二，工程图。

三，代码。

ReaderViewController.h

#import "ReaderViewController.h"#define ImageHeight 120static int num = 0;@interface ReaderViewController ()@end@implementation ReaderViewController- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil{  self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];  if (self) {    // Custom initialization  }  return self;}- (void)viewDidLoad{  [super viewDidLoad];  // Do any additional setup after loading the view.    //字体的颜色  self.navigationController.navigationBar.tintColor = [UIColor colorWithRed:248.0/255.0 green:172.0/255.0 blue:37.0/255.0 alpha:1.0];  //导航栏背景图  [self addBackgroundView:@"1.png"];    //左侧删除按钮  UIBarButtonItem *rightBarButton = [[UIBarButtonItem alloc]                    initWithTitle:@"delete"                    style:UIBarButtonItemStyleBordered                    target:self                    action:@selector(dele)];  //右侧增加按钮  UIBarButtonItem *leftBarButton = [[UIBarButtonItem alloc]                   initWithBarButtonSystemItem:UIBarButtonSystemItemAdd                   target:self                   action:@selector(add)];    self.navigationItem.rightBarButtonItem = rightBarButton;  self.navigationItem.leftBarButtonItem = leftBarButton;    //scrollerView  scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, 320, 416)];  scrollView.contentSize=CGSizeMake(320,480);    //设置背景颜色  UIImage *backimg=[UIImage imageNamed:@"3.png"];  UIImageView *backview=[[UIImageView alloc] initWithImage:backimg];  backview.frame=CGRectMake(0, 0, 320, 480);  [self.view addSubview:backview];    [self.view addSubview:scrollView];  //重新刷新界面  [self reloadView];}//导航栏上标题-(void)addBackgroundView:(NSString*)image{    UIImageView *imgView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:image]];  imgView.frame = CGRectMake(0, 0, 320, 44);  [self.navigationController.navigationBar addSubview: imgView];    UILabel *title = [[UILabel alloc] initWithFrame:CGRectMake((320-150)/2, 0, 150, 44)];  [title setText:@"书架"];  [title setTextColor:[UIColor whiteColor]];  [title setTextAlignment:NSTextAlignmentCenter];  [title setShadowColor:[UIColor grayColor]];  [title setBackgroundColor:[UIColor clearColor]];  [title setFont:[UIFont boldSystemFontOfSize:20.0]];  [self.navigationController.navigationBar addSubview:title];}//添加一个书架-(void)add{    num++;    UIImage *backimg=[UIImage imageNamed:@"2.png"];  UIImageView *backview=[[UIImageView alloc] initWithImage:backimg];  backview.frame=CGRectMake(0, (num-1)*ImageHeight, 320, ImageHeight);  backview.tag = num+100;    [scrollView addSubview:backview];    if (num>3) {    scrollView.contentSize=CGSizeMake(320,num*ImageHeight);  }}//删除一个书架-(void)dele{    if (num<=0) {    return;  }    for (UIView *view in scrollView.subviews) {    if(view.tag == (num+100))      [view removeFromSuperview];  }    num--;    if (num>3) {    scrollView.contentSize=CGSizeMake(320,num*ImageHeight);  }  }//主界面初始化-(void)reloadView{    NSLog(@"reloadView");  //遍历当前界面的所有子界面，把子界面删除干净  for(UIView *view in scrollView.subviews){    [view removeFromSuperview];  }    scrollView.showsVerticalScrollIndicator=NO;  scrollView.showsHorizontalScrollIndicator=NO;  scrollView.delegate=self;  [scrollView setScrollEnabled:YES];  }- (void)didReceiveMemoryWarning{  [super didReceiveMemoryWarning];  // Dispose of any resources that can be recreated.}

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原标题：【代码笔记】点击加号增加书架，点击减号减少书架

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