NSData NSString char *之间 || NSData和NSArray的相互转换

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我是靠谱客的博主紧张书本，最近开发中收集的这篇文章主要介绍NSData NSString char *之间 || NSData和NSArray的相互转换，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

1.NSString 转化为 char*
  NSString *testString = @"this is a test";
  const char * testChar = [testString UTF8String];

2.char * 转化为 NSString
NSString *str = [NSString stringWithCString:testChar encoding:NSUTF8StringEncoding];

3.char * 转化 NSData
  方法一：
        char* testChar = (char*)malloc(sizeof(byte)*16);
        NSData *dataTest = [NSData dataWithBytes:testChar length:strlen(testChar)];
  方法二：
        先转化为NSString： NSString *testString = [[NSString alloc] initWithUTF8String:testChar]; 
        后NSString转:     NSData *dataTest = [testString dataUsingEncoding: NSUTF8StringEncoding];

5.NSData 转化 char *
  NSData dataTest;
  char* testChar = [dataTest bytes];

6.NSData 转化 NSString;
  NSData* dataTest;
  NSString* testString= [[NSString alloc] initWithData:dataTest encoding:NSUTF8StringEncoding];

7.NSString 转化 NSData对象
  NSData* testData = [@"testdata" dataUsingEncoding:NSUTF8StringEncoding];

8.NSArray与NSData

    NSArray *arr1 = [[NSArray alloc]initWithObjects:@"HMT",@"WDQ",nil];
    NSData *data = [NSKeyedArchiver archivedDataWithRootObject:arr1];
    NSArray *arr2 = [NSKeyedUnarchiver unarchiveObjectWithData:data];
    NSLog(@"arr2 = %@",arr2);

9.image与NSData

if (UIImagePNGRepresentation(image) == nil) {

            data = UIImageJPEGRepresentation(image, 1);

        } else {

            data = UIImagePNGRepresentation(image);
}