[iOS] How to read byte in NSData?

如何從NSData讀Byte? 

NSData * theData = [NSData dataWithContentsOfFile: path];
const char* theBytes = (const char*)[theData bytes];

那讀幾個Byte?

NSRange range = NSMakeRange(location, length);

NSData *someData = [theData subdataWithRange:range]; 
const char* theBytes = (const char*)[someData bytes];

[iOS] The color of the back barbutton in Navigationbar.

Try to set this.

self.navigationController.navigationBar.tintColor

not

self.navigationItem.backBarButtonItem.tintColor

[iOS] x duplicate symbols for architecture xxxxxx

x duplicate symbols for architecture xxxxxx

之前有遇到過，有解過，但是忘記

現在記錄下來

是因為import的.h打成.m 所以才會這樣。