Iphone 支持以下圖像類型: PNG, JPG, THM, JPEG, TIF, TIFF, GIF, BMP, BMPF, ICO, CUR, XBM, PDF.
1.從應用程序包中加載圖像
myImage = [UIImage imageNamed:@"icon.png" ];NSString *path = [[NSBundle mainBundle] pathForResource:@"icon" ofType"@"png" ];myImage = [UIImage imageWithContentsOfFile:path]; |
2.從沙盒中加載圖像
查找Documents文件夾的標準方法:
NSArray *paths = [NSSearchPathForDirectoriesIndomains( NSDocumentDirectory, NSUserDomainMask, YES ) ];return [paths lastObject];NSString *documentsFolder(){ return [NSHomeDirectory() stringByAppendingPathComponent:@"Documents" ];} |
如果要加載圖像,將圖像文件名添加刀返回的路徑中,並告訴UIImage使用這些內容創建一副新圖像.
下面代碼是從頂層文檔文件夾中加載一個名爲image.png 的文件,然後返回由該數據初始化的一個UIImage 實例.
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path = [documentsFolder( ) stringByAppendingPathComponent:@"image.png"];return [UIImage imageWithContentsOfFile:path]; |
3.從URL中加載圖像
UIImage類可以直接從NSData實例中加載圖像.但是他不能直接從URL字符串或者NSURL對象加載圖像.
所以,只能使用相關數據創建新圖像.
eg:
NSURL *url = [NSURL URLWithString:@"
http://www.baidu.com/image/image.png"];UIImage *image = [UIImage imageWithData:[NSData dataWithContentsOfURL:url]]; |
可以用一個簡單的方法來處理這個過程,只需提供一個可獲取UIImage的URL字符串即可.
下面的方法接受一個參數,即一個URL字符串
+ (UIImage *) imageFromURLString: (NSString *)urlstring{ //This call is synchronous and blocking return [UIImage imageWithData:[NSData dataWithContentsOfURL:[ NSURL URLWithString:urlstring ]]];} |
4.從相冊加載數據
UIImagePickerController 類幫主用戶從Iphone相冊中選擇圖像.
二.加載圖像文件
//-------------------//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@endNSString *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.weather.com/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:));}@endIphone 支持以下圖像類型: PNG, JPG, THM, JPEG, TIF, TIFF, GIF, BMP, BMPF, ICO, CUR, XBM, PDF.