iOS 对NSString进行扩展(Extention),使其SHA224/SHA256/SHA384/SHA512
首先要引入头文件需要.m文件引入头文件#import#importSHA224代码-(NSString*)SHA224{constchar*cstr=[selfcStringUsingEncoding:NSUTF8StringEncoding];//注意这里的编码格式NSData*data=[NSDatadataWithBytes:cstrlength:self.length];uint8_tdi