IOS

Iphone 支持以下图像类型: PNG, JPG, THM, JPEG, TIF, TIFF, GIF, BMP, BMPF, ICO, CUR, XBM, PDF.

1.从应用程序包中加载图像

myImage = [UIImage imageNamed:@"icon.png" ]; NSString *path = [[NSBundle mainBundle] pathForResource:@"icon" ofType"@"png" ]; myImage = [UIImage imageWithContentsOfFile:path];

2.从沙盒中加载图像
查找Documents文件夹的标准方法:

NSArray *paths = [NSSearchPathForDirectoriesIndomains( NSDocumentDirectory, NSUserDomainMask, YES ) ]; return [paths lastObject]; NSString *documentsFolder() {      return [NSHomeDirectory() stringByAppendingPathComponent:@"Documents" ]; }

如果要加载图像,将图像文件名添加刀返回的路径中,并告诉UIImage使用这些内容创建一副新图像.
下面代码是从顶层文档文件夹中加载一个名为image.png 的文件,然后返回由该数据初始化的一个UIImage 实例.

1 2	path = [documentsFolder( )  stringByAppendingPathComponent:@"image.png"]; return [UIImage imageWithContentsOfFile:path];

3.从URL中加载图像
UIImage类可以直接从NSData实例中加载图像.但是他不能直接从URL字符串或者NSURL对象加载图像.
所以,只能使用相关数据创建新图像.
eg:

NSURL *url = [NSURL URLWithString:@" http://www.baidu.com/image/image.png"]; UIImage *image = [UIImage imageWithData:[NSData dataWithContentsOfURL:url]];

可以用一个简单的方法来处理这个过程,只需提供一个可获取UIImage的URL字符串即可.
下面的方法接受一个参数,即一个URL字符串

+ (UIImage *) imageFromURLString: (NSString *)urlstring {     //This call is synchronous and blocking    return [UIImage imageWithData:[NSData dataWithContentsOfURL:[ NSURL URLWithString:urlstring ]]]; }

4.从相册加载数据
UIImagePickerController 类帮主用户从Iphone相册中选择图像.

二.加载图像文件

//-------------------

//ImageHelper-Files.h 文件

//--------------------

#import <UIKit/UIKit.h>

@interface ImageHelper : NSObject

@end

@interface ImageHelper (Files)

+ (UIImage *) imageNamed: (NSString *) aName;

+ (UIImage *) imageFromURLString: (NSString *) urlstring;

+ (NSArray *) DCIMImages;

+ (UIImage *) DCIMImageNamed: (NSString *) aName;

@end

//-------------------

//ImageHelper-Files.m 文件

//--------------------

#import "ImageHelper-Files.h"

@implementation ImageHelper

@end

NSString *documentsFolder()

{

    return [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];

}

NSString *bundleFolder()

{

    return [[NSBundle mainBundle] bundlePath];

}

NSString *DCIMFolder()

{

    return [NSHomeDirectory() stringByAppendingPathComponent:@"../../Media/DCIM"];

}

@implementation ImageHelper (Files)

+ (NSString *) pathForItemNamed: (NSString *) fname inFolder: (NSString *) path

{

    NSString *file;

    NSDirectoryEnumerator *dirEnum = [[NSFileManager defaultManager] enumeratorAtPath:path];

    while (file = [dirEnum nextObject])

    if ([[file lastPathComponent] isEqualToString:fname])

        return [path stringByAppendingPathComponent:file];

    return nil;

}

// Searches bundle first then documents folder

+ (UIImage *) imageNamed: (NSString *) aName

{

    NSString *path = [ImageHelper pathForItemNamed:aName inFolder:bundleFolder()];

    path = path ? path : [ImageHelper pathForItemNamed:aName inFolder:documentsFolder()];

    if (!path) return nil;

    return [UIImage imageWithContentsOfFile:path];

}

+ (UIImage *) imageFromURLString: (NSString *) urlstring

{

    NSURL *url = [NSURL URLWithString:urlstring];

    return [UIImage imageWithData:[NSData dataWithContentsOfURL:url]];

}

+ (NSArray *) DCIMImages

{

    NSString *file;

    NSMutableArray *results = [NSMutableArray array];

    NSDirectoryEnumerator *dirEnum = [[NSFileManager defaultManager] enumeratorAtPath:DCIMFolder()];

    while (file = [dirEnum nextObject]) if ([file hasSuffix:@"JPG"]) [results addObject:file];

    return results;

}

+ (UIImage *) DCIMImageNamed: (NSString *) aName

{

    NSString *path = [ImageHelper pathForItemNamed:aName inFolder:DCIMFolder()];

    return [UIImage imageWithContentsOfFile:path];

}

@end

//-------------------

TestBedViewController.h 文件

//--------------------

#import <UIKit/UIKit.h>

#import "ImageHelper-Files.h"

#define COOKBOOK_PURPLE_COLOR [UIColor colorWithRed:0.20392f green:0.19607f blue:0.61176f alpha:1.0f]

#define BARBUTTON(TITLE, SELECTOR) [[[UIBarButtonItem alloc] initWithTitle:TITLE style:UIBarButtonItemStylePlain target:self action:SELECTOR] autorelease]

#define SETIMAGE(X) [(UIImageView *)self.view setImage:X]

const int NUM_OPTIONS = 4;

int which = 0;

@interface TestBedViewController : UIViewController

@end

@implementation TestBedViewController

- (void) action: (id) sender

{

    switch (which)

    {

        case 0:

            // Load image from web

            self.title = @"URL-based image";

            SETIMAGE([ImageHelper imageFromURLString:@"http://image./images/maps/current/curwx_600x405.jpg"]);

            break;

        case 1:

            // use UIImage's imageNamed: with caching

            self.title = @"imageNamed:";

            SETIMAGE([UIImage imageNamed:@"BFlyCircle.png"]);

            break;

        case 2:

            // Use the Image Helper version of imageNamed:

            self.title = @"Image Helper";

            SETIMAGE([ImageHelper imageNamed:@"icon.png"]);

            break;

        case 3:

            // Load normal background image from bundle

            self.title = @"Contents of file";

            SETIMAGE([UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"cover320x416" ofType:@"png"]]);

            break;

        default:

            break;

    }

    NSString *next = [NSString stringWithFormat:@"Example %d", (which = (which + 1) % NUM_OPTIONS) + 1];

    self.navigationItem.rightBarButtonItem = BARBUTTON(next, @selector(action:));

}

- (void) viewDidLoad

{

    self.navigationController.navigationBar.tintColor = COOKBOOK_PURPLE_COLOR;

    self.navigationItem.rightBarButtonItem = BARBUTTON(@"Example 1", @selector(action:));

}

@end

Iphone 支持以下图像类型: PNG, JPG, THM, JPEG, TIF, TIFF, GIF, BMP, BMPF, ICO, CUR, XBM, PDF.