解决 NSURL 不能直接处理中文方法:

NSString * query = [NSString stringWithString:@"http://www.google.com/?q=苹果"];
NSString * urlString = [query stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSURL * requesturl = [NSURL URLWithString:urlString];