斯威夫特3:

let documentsURL = try! FileManager().url(for: .documentDirectory,
                                          in: .userDomainMask,
                                          appropriateFor: nil,
                                          create: true)

．.． 给出文档目录的文件URL。下面检查是否有一个名为foo.html的文件:

let fooURL = documentsURL.appendingPathComponent("foo.html")
let fileExists = FileManager().fileExists(atPath: fooURL.path)

objective - c:

NSString* documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];

NSString* foofile = [documentsPath stringByAppendingPathComponent:@"foo.html"];
BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:foofile];

检查document/catchimage路径下是否存在文件:

NSString *stringPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)objectAtIndex:0];
NSString *tempName = [NSString stringWithFormat:@"%@/catchimage/%@.png",stringPath,@"file name"];
NSLog(@"%@",temName);
if([[NSFileManager defaultManager] fileExistsAtPath:temName]){
    // ur code here
} else {
    // ur code here** 
}

苹果公司建议不要依赖fileExistAtPath:方法。如果文件不存在，最好尝试打开文件并处理错误。

NSFileManager Class Reference Note: Attempting to predicate behavior based on the current state of the file system or a particular file on the file system is not recommended. Doing so can cause odd behavior or race conditions. It's far better to attempt an operation (such as loading a file or creating a directory), check for errors, and handle those errors gracefully than it is to try to figure out ahead of time whether the operation will succeed. For more information on file system race conditions, see “Race Conditions and Secure File Operations” in Secure Coding Guide.

来源:苹果开发者API参考

来自安全编码指南。

To prevent this, programs often check to make sure a temporary file with a specific name does not already exist in the target directory. If such a file exists, the application deletes it or chooses a new name for the temporary file to avoid conflict. If the file does not exist, the application opens the file for writing, because the system routine that opens a file for writing automatically creates a new file if none exists. An attacker, by continuously running a program that creates a new temporary file with the appropriate name, can (with a little persistence and some luck) create the file in the gap between when the application checked to make sure the temporary file didn’t exist and when it opens it for writing. The application then opens the attacker’s file and writes to it (remember, the system routine opens an existing file if there is one, and creates a new file only if there is no existing file). The attacker’s file might have different access permissions than the application’s temporary file, so the attacker can then read the contents. Alternatively, the attacker might have the file already open. The attacker could replace the file with a hard link or symbolic link to some other file (either one owned by the attacker or an existing system file). For example, the attacker could replace the file with a symbolic link to the system password file, so that after the attack, the system passwords have been corrupted to the point that no one, including the system administrator, can log in.

斯威夫特2.0

这是如何检查文件是否存在使用Swift

func isFileExistsInDirectory() -> Bool {
    let paths = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true)
    let documentsDirectory: AnyObject = paths[0]
    let dataPath = documentsDirectory.stringByAppendingPathComponent("/YourFileName")

    return NSFileManager.defaultManager().fileExistsAtPath(dataPath)
}

如果你以不同的方式设置文件系统，或者寻找不同的方法来设置文件系统，然后检查文件是否存在于文档文件夹中，这里有另一个例子。同时显示动态检查

for (int i = 0; i < numberHere; ++i){
    NSFileManager* fileMgr = [NSFileManager defaultManager];
    NSString *documentsDirectory = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
    NSString* imageName = [NSString stringWithFormat:@"image-%@.png", i];
    NSString* currentFile = [documentsDirectory stringByAppendingPathComponent:imageName];
    BOOL fileExists = [fileMgr fileExistsAtPath:currentFile];
    if (fileExists == NO){
        cout << "DOESNT Exist!" << endl;
    } else {
        cout << "DOES Exist!" << endl;
    }
}

斯威夫特3:

let documentsURL = try! FileManager().url(for: .documentDirectory,
                                          in: .userDomainMask,
                                          appropriateFor: nil,
                                          create: true)

．.． 给出文档目录的文件URL。下面检查是否有一个名为foo.html的文件:

let fooURL = documentsURL.appendingPathComponent("foo.html")
let fileExists = FileManager().fileExists(atPath: fooURL.path)

objective - c:

NSString* documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];

NSString* foofile = [documentsPath stringByAppendingPathComponent:@"foo.html"];
BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:foofile];