1.首先獲取要寫入文件的路徑
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentDirectory = [paths objectAtIndex:0];
NSString *fileName = [NSString stringWithFormat:@"log.txt"];// 注意不是NSData!
NSString *logFilePath = [documentDirectory stringByAppendingPathComponent:fileName];
// 先刪除已經(jīng)存在的文件
NSFileManager *defaultManager = [NSFileManager defaultManager];
[defaultManager removeItemAtPath:logFilePath error:nil];
// 將log輸入到文件
2.重定向輸出
freopen([logFilePath cStringUsingEncoding:NSASCIIStringEncoding], "a+", stdout);
freopen([logFilePath cStringUsingEncoding:NSASCIIStringEncoding], "a+", stderr);
