iOS -- 本地存储图片和沙盒机制
先上本地存储图片的代码：
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor redColor];
NSString *filePath = [self getFilePathWithImageName:@"good_coupon_bg"];
BOOLisExist = [selfisFileExistWithFilePath:filePath];
if (!isExist){ // 如果该图片不存在，则删除老图片，下载新图片
[self downloadAdImageWithImageName:@"good_coupon_bg"];
}else{
UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
btn.frame=CGRectMake(100,100,100,100);
[btnsetImage:[UIImage imageWithContentsOfFile:filePath] forState:UIControlStateNormal];
[self.viewaddSubview:btn];
}
}
/**
* 删除旧图片
*/
- (void)deleteOldImage {
NSString *imageName = [[NSUserDefaults standardUserDefaults] valueForKey:@"sds"];
if(imageName) {
NSString*filePath = [selfgetFilePathWithImageName:imageName];
NSFileManager *fileManager = [NSFileManager defaultManager];
[fileManagerremoveItemAtPath:filePatherror:nil];
}
}
/**
* 判断文件是否存在
*/
- (BOOL)isFileExistWithFilePath:(NSString*)filePath {
NSFileManager *fileManager = [NSFileManager defaultManager];
BOOLisDirectory =FALSE;
return[fileManagerfileExistsAtPath:filePathisDirectory:&isDirectory];
}
/**
* 根据图片名拼接文件路径
*/
- (NSString*)getFilePathWithImageName:(NSString*)imageName {
if(imageName) {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory,NSUserDomainMask, YES);
NSString *filePath = [[paths objectAtIndex:0] stringByAppendingPathComponent:imageName];
returnfilePath;
}
return nil;
}
/**
* 下载新图片
*/
- (void)downloadAdImageWithImageName:(NSString*)imageName {
UIImage *image = [UIImage imageNamed:@"good_coupon_bg"];
NSString*filePath = [selfgetFilePathWithImageName:imageName];// 保存文件的名称
if ([UIImagePNGRepresentation(image) writeToFile:filePath atomically:YES]) {// 保存成功
NSLog(@"保存成功");
[self deleteOldImage];
[[NSUserDefaults standardUserDefaults] setValue:imageName ?:@"" forKey:@"sds"];
[[NSUserDefaults standardUserDefaults] synchronize];
}else{
NSLog(@"保存失败");
}
}
解释：- (NSString*)getFilePathWithImageName:(NSString*)imageName 这个方法只是要把将要保存的图片保存到这个方法设置的路径下。（但是此时在沙盒里面，（这里是沙盒里面的Cache）是看不到这个路径的，因为图片还没有成功保存到本地，所以不会在Cache下产生我们设置的文件路径）
直到[UIImagePNGRepresentation(image) writeToFile:filePath atomically:YES]返回YES，也就是图片成功保存到我们设置好的路径下（文件下），我们才会在Cache下看到我们设置的路径，（也就是图片保存的路径）
我们通过[NSUserDefaults standardUserDefaults]保存的值，是存在Library ->Preferences下面（以plist文件形式保存）
文件夹应该就是目录吧
/**
* 创建文件夹/目录(返回创建结果)
*/
-(BOOL)createDir:(NSString*)fileName{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
// NSString *documentsDirectory = [paths objectAtIndex:0];
// NSString * path = [NSString stringWithFormat:@"%@/%@",documentsDirectory,fileName];
NSString* path = [[pathsobjectAtIndex:0] stringByAppendingPathComponent:fileName];
NSFileManager *fileManager = [NSFileManager defaultManager];
BOOLisDir;
if (![fileManagerfileExistsAtPath:pathisDirectory:&isDir]) {//先判断目录是否存在，不存在才创建
BOOL res=[fileManager createDirectoryAtPath:path withIntermediateDirectories:YES attributes:nil error:nil];
returnres;
}else return NO;
}
* NSString *documentsDirectory = [paths objectAtIndex:0];
NSString * path = [NSString stringWithFormat:@"%@/%@",documentsDirectory,fileName];
上面这两句代码跟这行代码是一样的
NSString* path = [[pathsobjectAtIndex:0] stringByAppendingPathComponent:fileName];
/**
* 创建文件(返回创建结果)
*/
-(BOOL)createFile:(NSString*)path{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *testPath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"test"];//在传入的路径下创建test.c文件
BOOL res = [fileManagercreateFileAtPath:testPathcontents:nilattributes:nil];
//通过data创建数据
// [fileManager createFileAtPath:testPath contents:NULL attributes:nil];
returnres;
}
/**
* 读文件数据
*/
-(void)readFile:(NSString*)path{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *testPath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"test"];
//方法1:
// NSData * data = [NSData dataWithContentsOfFile:path];
// NSString * content = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
//方法2:
NSString * content = [NSString stringWithContentsOfFile:testPath encoding:NSUTF8StringEncoding error:nil];
NSLog(@"文件读取成功: %@",content);
}
/**
* 根据路径删除文件(返回删除结果)
*/
-(BOOL)deleteFileByPath:(NSString*)path{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *testPath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"test"];
NSFileManager *fileManager = [NSFileManager defaultManager];
BOOLres=[fileManagerremoveItemAtPath:testPatherror:nil];
NSLog(@"文件是否存在: %@",[fileManagerisExecutableFileAtPath:path]?@"YES":@"NO");
returnres;
}
// 真机下的路径
/var/mobile/Containers/Data/Application/976A0BCC-76C2-4AE9-9865-53CDC0860597
