UIScrollViewHomework--SimplePhot

做一个简易的相册, 每个图片都可以放大缩小,并且翻到第二张图时,再翻回来就变成原来的大小

//1.创建视图控制器RootViewController,并在Appdelegate.m中将其设为根视图控制器

RootViewController *rootVC = [[RootViewController alloc]init];

self.window.rootViewController = rootVC;

[rootVCrelease];

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//2.在RootViewController.m中进行实现

#import "RootViewController.h"

//若要实现视图的缩放与翻回还原, 需要用到代理

@interface RootViewController () {

//将大滚动视图和其上小滚动视图元素的位置下标设为全局变量

UIScrollView *photoScollView;

NSInteger flag;

}

@end

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@implementation RootViewController

- (void)viewDidLoad {

[superviewDidLoad];

//当前屏幕的大小

CGSizescreenSize = [UIScreen mainScreen].bounds.size;

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//相片名字集合

NSArray*nameArray = @[@"1", @"2", @"3", @"4", @"5", @"6", @"7", @"8",@"9", @"10", @"11", @"12", @"13", @"14", @"15",@"16", @"17", @"18", @"19", @"20", @"21", @"22", @"23",@"24"];

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//元素下标起始为0

_flag =0;

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//创建大的滚动视图

photoScollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0,0, screenSize.width, screenSize.height)];

photoScollView.contentSize = CGSizeMake(screenSize.width *nameArray.count, screenSize.height);

photoScollView.pagingEnabled = YES;

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//为大滚动视图设置代理

photoScollView.delegate = self;

photoScollView.showsHorizontalScrollIndicator = NO;

[self.viewaddSubview:photoScollView];

[photoScollView release];

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//通过for循环, 设置与相片数量相等的小滚动视图, 并将相片放到小滚动视图上

for(NSInteger i = 0; i < nameArray.count; i++) {

//创建小滚动视图

UIScrollView *smallScrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(i * screenSize.width, 0, screenSize.width,screenSize.height)];

//缩放

smallScrollView.minimumZoomScale = 0.5;

smallScrollView.maximumZoomScale = 2;

smallScrollView.zoomScale = 1.0;

//为小滚动视图设置代理

smallScrollView.delegate = self;

[photoScollView addSubview:smallScrollView];

[smallScrollView release];

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//创建相片视图

UIImageView *imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:nameArray[i]]];

imageView.frame = CGRectMake(0, 0, screenSize.width,screenSize.height);

//为相片视图设置tag值

imageView.tag = 100;

[smallScrollView addSubview:imageView];

[imageView release];

}

}

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#pragma mark - UIScrollViewDelegate

//对哪个视图进行缩放

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView{

if(scrollView != photoScollView) {

return [scrollView viewWithTag:100];

} else{

return nil;

}

}

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//视图结束拖拽时实现视图还原

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{

if(scrollView == photoScollView) {

NSInteger currentPage = photoScollView.contentOffset.x / 375;

if (currentPage != flag) {

UIScrollView *smallScrollView = [photoScollView.subviewsobjectAtIndex:flag];

smallScrollView.zoomScale = 1.0;

flag = currentPage;

}

}

}

@end

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