使用NSData来加载文件

1. Loading Data from Files and URLs

// Assuming that there is a text file at /Examples/Test.txt:
NSString* filePath = @"/Examples/Test.txt";
NSData* loadedData = [NSData dataWithContentsOfFile:filePath];

2. Load NSData into a string

NSString* loadedString = [[NSString alloc] initWithData:loadedData
encoding:NSUTF8StringEncoding];

3. Write NSData into a file

// Here, loadedData is an NSData object
NSString* filePath = @"/Examples/Test.txt";
[loadedData writeToFile:filePath atomically:YES];