UI_如何实现点击图片之后放大,或缩放功能

//  ViewController.m
//  01_猜图游戏
#import "ViewController.h"
#import "DXQuestion.h"
@interface ViewController ()
@property (nonatomic, strong) NSArray *questions;// 记录icon button的原始的frame
@property (nonatomic, assign) CGRect iconFrame;

@property (nonatomic, weak) UIButton *coverView;

@end

@implementation ViewController

// 点击了大图按钮
- (IBAction)didClickShowBigImageButton:(UIButton *)sender {
    
    
    // 0. 记录 btnIcon 的frame
    self.iconFrame = self.btnIcon.frame;
    
    // 1. 创建一个和屏幕一样大小的半透明UIView, 用来遮盖整个界面
    UIButton *coverView = [[UIButton alloc] init];
    coverView.backgroundColor = [UIColor blackColor];
    coverView.alpha = 0.0;
    coverView.frame = self.view.bounds;
    // 为半透明背景添加一个单击事件
    [coverView addTarget:self action:@selector(didClickCoverView:) forControlEvents:UIControlEventTouchUpInside];
    
    [self.view addSubview:coverView];
    self.coverView = coverView;
    
    // 需要把"头像按钮", 放置在coverView的前面
    [self.view bringSubviewToFront:self.btnIcon];

    // 2. 讲头像按钮（图片按钮）放大
    CGFloat iconW = self.view.bounds.size.width;
    CGFloat iconH =iconW;
    CGFloat iconX = 0;
    CGFloat iconY = (self.view.bounds.size.height - iconH) * 0.5;
    
    [UIView animateWithDuration:0.5 animations:^{
        coverView.alpha = 0.6;
        self.btnIcon.frame = CGRectMake(iconX, iconY, iconW, iconH);
    }];
    
}

// 点击了"半透明背景"按钮
- (void)didClickCoverView:(UIButton *)sender {
    
    // 1. 让"头像按钮"通过动画的方式回到原来的位置
    [UIView animateWithDuration:0.5 animations:^{
        
        self.btnIcon.frame = self.iconFrame;
        // 2. 让"半透明背景"通过动画的方式透明度变成0, 然后从父容器中移除
        self.coverView.alpha = 0.0;
    } completion:^(BOOL finished) {
        [self.coverView removeFromSuperview];
    }];
}

// 点击了下一题按钮
- (IBAction)didClickNextQuestionButton:(UIButton *)sender {
    
    // 1. 切换题目的显示
    [self nextQuestion];
    
}


// 点击了中间的图片按钮
- (IBAction)didClickIconButton:(UIButton *)sender {
    
    // 根据是否已经创建了coverView, 来决定是应该放大还是缩小
    if (self.coverView == nil) {
        // 放大
        [self didClickShowBigImageButton:nil];
    } else {
        // 缩小
        [self didClickCoverView:self.coverView];
    }
    
}