iOS 基本数据类型之NSData
1 nsdata
作用：
用于存储二进制的数据类型
nadat类提供一种简单的方式，它用来设置缓存区。将文件的内容读入到缓存区。或者将缓存区中的内容写到一个文件。
不变缓存区（nsdata类） 也可定义可变缓存区类（nsmutableData类）
NSData 、 NSString互转：
NSData * data = [str dataUsingEncoding:NSUTF8StringEncoding]; //NSString转换成NSData类型
NSString * newStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSData 、Byte 互转
NSString *testString = @"1234567890";
NSData *testData = [testString dataUsingEncoding: NSUTF8StringEncoding];
Byte *testByte = (Byte *)[testData bytes];
Byte byte[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23};
NSData *adata = [[NSData alloc] initWithBytes:byte length:24];
NSData转UIImage
UIImage *aimage = [UIImage imageWithData: data];
NSData转NSDictionary
@interface NSDictionary (Helpers)
+ (NSDictionary *)dictionaryWithContentsOfData:(NSData *)data;
@end
@implementation NSDictionary (Helpers)
+ (NSDictionary *)dictionaryWithContentsOfData:(NSData *)data {
CFPropertyListRef plist = CFPropertyListCreateFromXMLData(kCFAllocatorDefault, (CFDataRef)data,
kCFPropertyListImmutable,
NULL);
if(plist == nil) return nil;
if ([(id)plist isKindOfClass:[NSDictionary class]]) {
return [(NSDictionary *)plist autorelease];
}
else {
CFRelease(plist);
return nil;
}
}
@end
NSData 应用场景
将文件的内容读入内存缓冲区
NSData *fileData;
NSFileManager *fileManager = [[NSFileManager alloc]init];
fileData = [fileManager contentsAtPath:path];
将缓冲区的内容写入到一个文件中
NSFileManager *fileManager = [[NSFileManager alloc]init];
[fileManager createFileAtPath:path contents:fileData attributes:nil];
天下文章一大抄 该文内容根据以下博客整理
http://www.cnblogs.com/GISerYang/p/3345350.html
http://bj007.blog.51cto.com/1701577/538990/
http://blog.csdn.net/jerryvon/article/details/7350567
http://www.cnblogs.com/duchengdong/archive/2012/03/29/2422997.html
http://www.myexception.cn/operating-system/1808379.html