objective-c - 使用base64时出现奇怪的目标c错误

Question

我刚刚尝试了以下代码段，但我遇到了错误：-

#import "JSONKit.h"
#import "Base64.h"
#import <Foundation/Foundation.h>

int main() { 
NSMutableDictionary *dict = [NSMutableDictionary dictionary]; [dict setObject:(id)@"value" forKey:(id)@"key"];

for(id key in dict) NSLog(@"%@\t%@\n", key, [dict objectForKey:key]);

[Base64 initialize]; 
NSData *jsonstr = [dict JSONStringWithOptions:JKSerializeOptionNone error:nil]; 
NSString *val = [Base64 encode: jsonstr]; 
NSLog(@"%@\n", val);

return 0; 
}

我得到的错误是：-

test.m: In function ‘main’:
test.m:13: warning: incompatible Objective-C types initializing ‘struct NSString *’, expected ‘struct NSData *’
Undefined symbols:
  "_OBJC_CLASS_$_Base64", referenced from:
      __objc_classrefs__DATA@0 in cc23xlpr.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

为了消除警告，我将一行更改为：-

NSData *jsonstr = (NSData *)[dict JSONStringWithOptions:JKSerializeOptionNone error:nil];

但是，错误仍然存​​在——对 Objective-C 来说是新手，我发现这个错误非常神秘，有人可以帮助我理解问题的根源/解决方案吗？

Answer 1

我想，该[dict JSONStringWithOptions:JKSerializeOptionNone error:nil]方法返回字符串，如果你想将该字符串序列化为 NSData ，你应该遵循：

[Base64 initialize]; 
NSString *jsonStr = [dict JSONStringWithOptions:JKSerializeOptionNone error:nil]; 
NSData *jsonstrData = [jsonStr dataUsingEncoding:NSUTF8StringEncoding];
NSString *val = [Base64 encode: jsonstrData]; 
NSLog(@"%@\n", val);