老是有这样的warning，今天发现云信对NSInteger用的%zd，以前没见过，遂网络之，在stack overflow得到了解答
You can also use%zd(NSInteger) and%tu(NSUInteger) when logging to the console.
NSInteger integer = 1;
NSLog(@"first number: %zd", integer);
NSUInteger uinteger = 1;
NSLog(@"second number: %tu", uinteger);
