【代码笔记】显示图片的各种方式

代码：

- (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view.
 UIImageView *img=[[UIImageView alloc]initWithFrame:CGRectMake(50, 100, 200, 200)]; img.backgroundColor=[UIColor redColor]; [self.view addSubview:img]; //从网络下载图片，保存，并用 UIImageView 从保存中显示
    NSString * documentsDirectoryPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0]; NSLog(@"保存路径:%@",documentsDirectoryPath); //Get Image From URL
    UIImage * imageFromURL = [self getImageFromURL:@"http://file.duteba.com/phone/2009/04/5/ftGxL8kcUL.jpg"]; //Save Image to Directory
    [self saveImage:imageFromURL withFileName:@"MyImage" ofType:@"jpg" inDirectory:documentsDirectoryPath]; //Load Image From Directory
    UIImage * imageFromWeb = [self loadImage:@"MyImage" ofType:@"jpg" inDirectory:documentsDirectoryPath]; [img setImage:imageFromWeb]; //取得目录下所有文件名
    NSArray *file = [[[NSFileManager alloc] init] subpathsAtPath:documentsDirectoryPath]; NSLog(@"%lu",(unsigned long)[file count]); NSLog(@"%@",file); } //从网络下载图片
-(UIImage *) getImageFromURL:(NSString *)fileURL { NSLog(@"执行图片下载函数"); UIImage * result; NSData * data = [NSData dataWithContentsOfURL:[NSURL URLWithString:fileURL]]; result = [UIImage imageWithData:data]; return result; } //将所下载的图片保存到本地
-(void) saveImage:(UIImage *)image withFileName:(NSString *)imageName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath { if ([[extension lowercaseString] isEqualToString:@"png"]) { [UIImagePNGRepresentation(image) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", imageName, @"png"]] options:NSAtomicWrite error:nil]; } else if ([[extension lowercaseString] isEqualToString:@"jpg"] || [[extension lowercaseString] isEqualToString:@"jpeg"]) { [UIImageJPEGRepresentation(image, 1.0) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", imageName, @"jpg"]] options:NSAtomicWrite error:nil]; } else { //ALog(@"Image Save Failed\nExtension: (%@) is not recognized, use (PNG/JPG)", extension);
        NSLog(@"文件后缀不认识"); } } //读取本地保存的图片
-(UIImage *) loadImage:(NSString *)fileName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath { UIImage * result = [UIImage imageWithContentsOfFile:[NSString stringWithFormat:@"%@/%@.%@", directoryPath, fileName, extension]]; return result; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated.
}

 

输出：

2015-10-13 13:43:09.989 从网络下载图片，保存，并用 UIImageView 从保存中显示[7260:182365] 保存路径:/Users/chenlihua/Library/Developer/CoreSimulator/Devices/78D1FCBF-9990-471F-9075-168F2CE949FE/data/Containers/Data/Application/52E9DF04-CC22-4834-A3C5-2261A5061032/Documents 2015-10-13 13:43:09.989 从网络下载图片，保存，并用 UIImageView 从保存中显示[7260:182365] 执行图片下载函数 2015-10-13 13:43:10.231 从网络下载图片，保存，并用 UIImageView 从保存中显示[7260:182365] 0
2015-10-13 13:43:10.231 从网络下载图片，保存，并用 UIImageView 从保存中显示[7260:182365] ( )