objective-c 数据类型转换
1. NSString 与 char *
char * -> NSString
NSString *str = @"abcde";
NSString *str = [NSString sttringWithFormat: @"%d%@", 10, @"abc"]
NSString -> char *
const char *s = [str UTF8String];
2. NSSTring 与 NSStirng
NSString *str1 = @"abcde";
NSString *str2 = [NSString stringWithString: str1];
NSString *str3 = [[NSString alloc] initWithString: str1];
3. NSData 与 NSString
NSString－>NSData
NSString *str = @"1234abcd";
NSData *data = [str dataUsingEncoding: NSUTF8StringEncoding];
NSData－> NSString
NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
4.NSData 与 Byte
NSData －> Byte数组
NSString *testString = @"1234567890";
NSData *testData = [testString dataUsingEncoding: NSUTF8StringEncoding];
Byte *testByte = (Byte *)[testData bytes];
for (int i=0; i < [testData length]; i++) {
NSLog(@"testByte = %d\n",testByte[i]);
}
Byte数组－> NSData
Byte byte[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
NSData *aData = [[NSData alloc] initWithBytes:byte length:10];
Byte数组－>16进制数
Byte *bytes = (Byte *)[aData bytes];
NSString *hexStr = @"";
for (int i = 0; i < [encryData length]; i++) {
NSString *newHexStr = [NSString stringWithFormat:@"%x",bytes[i]&0xff];///16进制数
if ([newHexStr length]==1)
hexStr = [NSString stringWithFormat:@"%@0%@",hexStr,newHexStr];
else
hexStr = [NSString stringWithFormat:@"%@%@",hexStr,newHexStr];
}
NSLog(@"bytes 的16进制数为:%@",hexStr);
16进制数－>Byte数组
// 将16进制数据转化成Byte 数组
NSString *hexString = @"3e435fab9c34891f"; //16进制字符串
int j=0;
Byte bytes[128]; ///3ds key的Byte 数组， 128位
for (int i = 0; i < [hexString length]; i++) {
int int_ch; /// 两位16进制数转化后的10进制数
unichar hex_char1 = [hexString characterAtIndex:i]; ////两位16进制数中的第一位(高位*16)
int int_ch1;
if (hex_char1 >= '0' && hex_char1 <='9')
int_ch1 = (hex_char1-48)*16; //// 0 的Ascll - 48
else if (hex_char1 >= 'A' && hex_char1 <='F')
int_ch1 = (hex_char1-55)*16; //// A 的Ascll - 65
else
int_ch1 = (hex_char1-87)*16; //// a 的Ascll - 97
i++;
unichar hex_char2 = [hexString characterAtIndex:i]; ///两位16进制数中的第二位(低位)
int int_ch2;
if (hex_char2 >= '0' && hex_char2 <='9')
int_ch2 = (hex_char2-48); //// 0 的Ascll - 48
else if (hex_char1 >= 'A' && hex_char1 <='F')
int_ch2 = hex_char2-55; //// A 的Ascll - 65
else
int_ch2 = hex_char2-87; //// a 的Ascll - 97
int_ch = int_ch1+int_ch2;
NSLog(@"int_ch=%d",int_ch);
bytes[j] = int_ch; ///将转化后的数放入Byte数组里
j++;
}
NSData *newData = [[NSData alloc] initWithBytes:bytes length:128];
NSLog(@"newData=%@",newData);
4. NSData 与 UIImage
NSData－>UIImage
UIImage *aimage = [UIImage imageWithData: imageData];
//例：从本地文件沙盒中取图片并转换为NSData
NSString *path = [[NSBundle mainBundle] bundlePath];
NSString *name = [NSString stringWithFormat:@"ceshi.png"];
NSString *finalPath = [path stringByAppendingPathComponent:name];
NSData *imageData = [NSData dataWithContentsOfFile: finalPath];
UIImage *aimage = [UIImage imageWithData: imageData];
UIImage－> NSData
NSData *imageData = UIImagePNGRepresentation(aimae);
6. NSData 与 CFDataRef
NSData *my_nsdata = (__bridge_transfer NSData*)my_cfdata;
NSData *my_nsdata = (__bridge NSData*)my_cfdata;
