IOS 對相冊圖片進行讀取、存儲到指定文件夾

這個示例程序主要用到了IOS中的UIImageView、UIImagePickerViewController、UIImage、NSFileManager等知識，結合這些知識構成一個小的應用程序，主要功能是對相冊圖片進行讀取、存儲到指定文件夾、從指定文件夾讀取出來。這方面的知識在正式項目中用的是比較多的。作Android開發中，常常會使用到將圖片保存到SD卡和從SD卡讀取圖片的操做，相比於Android在這方面的操做，IOS要方便許多。

 

基本功能是從相冊選取一張圖片，選完後顯示在界面的UIImageView控件中，點擊保存到文件夾按鈕後就將圖片保存到Documents下的ImageFile文件夾中，以image.png命名。退出程序下次進來時，能夠選擇從文件夾讀取圖片，若是有則讀取出來顯示在UIImageView上，若是沒有則提示文件不存在。

首先來看看最後效果：

·從相冊選取圖片後顯示在界面上

這裏對功能進行了一點改進，點擊打開相冊按鈕後出來一個UIActionSheet操做選項框，能夠選擇是從相機獲取圖片仍是從相冊獲取。代碼也作出了一點修改。

                          

·點擊保存到文件夾按鈕後提示信息

                           

 

·點擊讀取圖片按鈕後的提示信息（圖片不存在）

·若是存在則將圖片顯示出來

            

保存圖片成功後，按照前一篇文章提到的方法，能夠到Finder下查看文件信息：

 

下面是實現部分，首先看看佈局文件：

 

下面是代碼：

 

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController<UIImagePickerControllerDelegate,UINavigationControllerDelegate,UIActionSheetDelegate>

@property (retain, nonatomic) IBOutlet UIImageView *imageView;
@property (retain, nonatomic) UIButton *saveToFileButton;

//打開相冊
- (IBAction)openAlbum:(id)sender;

//從文件夾讀取圖片
- (IBAction)readImage:(id)sender;

@end

 

下面是ViewController.m文件

 

#import "ViewController.h"
//保存到文件夾按鈕的標籤，選取圖片前，這個按鈕是隱藏的
#define SAVE_BUTTON_TAG 101

@interface ViewController ()

@end

@implementation ViewController
@synthesize imageView = _imageView;
@synthesize saveToFileButton = _saveToFileButton;

- (void)viewDidLoad
{
    [super viewDidLoad];
    //根據設置的tag獲取按鈕控件
    self.saveToFileButton = (UIButton *)[self.view viewWithTag:SAVE_BUTTON_TAG];
    //添加對象事件
    [self.saveToFileButton addTarget:self action:@selector(saveToFileBtnTapped:) forControlEvents:UIControlEventTouchUpInside];
    //設置爲不可見
    self.saveToFileButton.hidden = YES;
}

- (void)viewDidUnload
{
    [self setImageView:nil];
    [self setSaveToFileButton:nil];
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

- (void)dealloc {
    [self.imageView release];
    [self.saveToFileButton release];
    [super dealloc];
}

- (IBAction)openAlbum:(id)sender {
    UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"選擇圖片" delegate:self cancelButtonTitle:@"取消" destructiveButtonTitle:nil otherButtonTitles:@"拍照",@"相冊", nil];
    [actionSheet showInView:self.view];
    [actionSheet release];
}

//從文件夾讀取圖片
- (IBAction)readImage:(id)sender {
    NSString *imagePath = [self imageSavedPath:@"image.png"];
    NSFileManager *fileManager = [NSFileManager defaultManager];
    //判斷文件是否存在
    if (![fileManager fileExistsAtPath:imagePath]) {
        UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Note" message:@"文件不存在" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
        [alertView show];
        [alertView release];
    }else {
        //從指定目錄讀取圖片
        UIImage *image = [UIImage imageWithContentsOfFile:imagePath];
        self.imageView.image = image;
    }
}

//保存到文件按鈕事件
- (void)saveToFileBtnTapped:(id)sender {
    NSString *imagePath = [self imageSavedPath:@"image.png"];
    BOOL isSaveSuccess = [self saveToDocument:self.imageView.image withFilePath:imagePath];

    if (isSaveSuccess) {
        UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"操做結果" message:@"保存圖片成功" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
        [alertView show];
        [alertView release];
    }else {
        UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"操做結果" message:@"保存圖片失敗" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
        [alertView show];
        [alertView release];
    }
}

//將選取的圖片保存到目錄文件夾下
-(BOOL)saveToDocument:(UIImage *) image withFilePath:(NSString *) filePath
{
    if ((image == nil) || (filePath == nil) || [filePath isEqualToString:@""]) {
        return NO;
    }

    @try {
        NSData *imageData = nil;
        //獲取文件擴展名
        NSString *extention = [filePath pathExtension];
        if ([extention isEqualToString:@"png"]) {
            //返回PNG格式的圖片數據
            imageData = UIImagePNGRepresentation(image);
        }else{
            //返回JPG格式的圖片數據，第二個參數爲壓縮質量：0:best 1:lost
            imageData = UIImageJPEGRepresentation(image, 0);
        }
        if (imageData == nil || [imageData length] <= 0) {
            return NO;
        }
        //將圖片寫入指定路徑
        [imageData writeToFile:filePath atomically:YES];
        return  YES;
    }
    @catch (NSException *exception) {
        NSLog(@"保存圖片失敗");
    }

    return NO;

}

//根據圖片名將圖片保存到ImageFile文件夾中
-(NSString *)imageSavedPath:(NSString *) imageName
{
    //獲取Documents文件夾目錄
    NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentPath = [path objectAtIndex:0];
    //獲取文件管理器
    NSFileManager *fileManager = [NSFileManager defaultManager];
    //指定新建文件夾路徑
    NSString *imageDocPath = [documentPath stringByAppendingPathComponent:@"ImageFile"];
    //建立ImageFile文件夾
    [fileManager createDirectoryAtPath:imageDocPath withIntermediateDirectories:YES attributes:nil error:nil];
    //返回保存圖片的路徑（圖片保存在ImageFile文件夾下）
    NSString * imagePath = [imageDocPath stringByAppendingPathComponent:imageName];
    return imagePath;
}

#pragma Delegate method UIImagePickerControllerDelegate
//圖像選取器的委託方法，選完圖片後回調該方法
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)image editingInfo:(NSDictionary *)editingInfo
{
    if (image != nil) {
        //選定照片後在界面顯示照片並把保存按鈕設爲可見
        self.imageView.image = image;
        self.saveToFileButton.hidden = NO;
    }
    //關閉圖像選擇器
    [self dismissModalViewControllerAnimated:YES];
}

-(void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{
    //獲取圖片選取器
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
    //指定代理
    imagePicker.delegate = self;
    //打開圖片後容許編輯
    imagePicker.allowsEditing = YES;

    //判斷圖片源的類型
    if (buttonIndex == 0) {
        if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
            //相機
            imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
        }
    }else if (buttonIndex == 1) {
        if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]){
            //圖片庫
            imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        }
//        if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeSavedPhotosAlbum]) {
//            //相冊
//            imagePicker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
//        }
    }else if (buttonIndex == [actionSheet cancelButtonIndex]) {
        return;
    }

    //打開圖片選擇模態視圖
    [self presentModalViewController:imagePicker animated:YES];
    [imagePicker release];

}

@end