ios 将Log信息写入文件

有时候我们为了调试需要将一些信息写入到文件，便于查看问题原因；

方式如下：

一、存储

 NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *logPath = [documentsDirectory stringByAppendingPathComponent:@"console.log"];
    freopen([logPath cStringUsingEncoding:NSASCIIStringEncoding],"a+",stderr);

二、读取

   NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *logPath = [documentsDirectory stringByAppendingPathComponent:@"console.log"];
//写入的内容
NSString *string = [[NSString alloc]initWithContentsOfFile:logPath encoding:NSUTF8StringEncoding error:nil];