base64字符串(base64String)-存的是image数据
NSData* data = [[NSData alloc] initWithBase64EncodedString:base64String options:0];
UIImage* image = [UIImage imageWithData:data];
base64字符串(base64String)-存的是image数据
NSData* data = [[NSData alloc] initWithBase64EncodedString:base64String options:0];
UIImage* image = [UIImage imageWithData:data];