从iOS上的二进制NSData减去字符串

Question

我有一个NSData的字节从我想要减去一个字符串。该NSData对象看起来像这样

01 00 00 04 40 00 00 00 00 41 41 41 41 48 47 5A 30 65 58 42 4E 4E 45 45 67 41 
41 41 41 41 45 30 30 51 53 42 74 63 44 51 79 61 58 4E 76 62 51 41 41 41 2B 39 
74 62 32 39 32 41 41 41 41 62 47 31 32 61 47 51 41 41 41 41 41 71 67 59 35 79 
36 6F 47 4F 63 73 41 41 4B 78 45 41 41 43 34 41 41 41 42 41 41 41 42 41 41 41 
41 41 41 41 41 41 41 41 41 41 41 41 41 41 51 41 41 41 41 41 41 41 41 41 41 41 

我想从“40 00 00 00”中第一次出现解压一切“34”

我怎么能做到这一点的第一次出现？

由于

果渣

Answer 1

不确定的哪些字节要，这里被提取的范围内的数据“40 00 00 00”之间，以“34”的第一次出现，并与该范围中删除的数据：

const NSUInteger dataLength = 130; 
unsigned char dataBytes[dataLength] = { 
0x01,0x00,0x00,0x04,0x40,0x00,0x00,0x00,0x00,0x41,0x41,0x41,0x41,0x48,0x47,0x5A, 
0x30,0x65,0x58,0x42,0x4E,0x4E,0x45,0x45,0x67,0x41,0x41,0x41,0x41,0x41,0x45,0x30, 
0x30,0x51,0x53,0x42,0x74,0x63,0x44,0x51,0x79,0x61,0x58,0x4E,0x76,0x62,0x51,0x41, 
0x41,0x41,0x2B,0x39,0x74,0x62,0x32,0x39,0x32,0x41,0x41,0x41,0x41,0x62,0x47,0x31, 
0x32,0x61,0x47,0x51,0x41,0x41,0x41,0x41,0x41,0x71,0x67,0x59,0x35,0x79,0x36,0x6F, 
0x47,0x4F,0x63,0x73,0x41,0x41,0x4B,0x78,0x45,0x41,0x41,0x43,0x34,0x41,0x41,0x41, 
0x42,0x41,0x41,0x41,0x42,0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41, 
0x41,0x41,0x41,0x41,0x41,0x41,0x51,0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41,0x41, 
0x41,0x41}; 
NSData *data = [NSData dataWithBytes:dataBytes length:130]; 

const NSUInteger startBytesLength = 4; 
unsigned char startBytes[startBytesLength] = {0x40, 0x00, 0x00, 0x00}; 
const NSUInteger stopBytesLength = 1; 
unsigned char stopBytes[stopBytesLength] = {0x34}; 


NSData *startData = [NSData dataWithBytes:startBytes length:startBytesLength]; 
NSData *stopData = [NSData dataWithBytes:stopBytes length:stopBytesLength]; 
NSRange startRange = [data rangeOfData:startData options:0 range:NSMakeRange(0, dataLength)]; 
NSUInteger start = startRange.location; 

NSRange stopRange = [data rangeOfData:stopData options:0 range:NSMakeRange(start+startBytesLength, dataLength-(start+startBytesLength))]; 
NSUInteger length = stopRange.location - start; 
NSUInteger stopLocation = stopRange.location+stopBytesLength; 

NSData *extractData = [data subdataWithRange:NSMakeRange(start, length)]; 
NSLog(@"extractData: %@", extractData); 

NSMutableData *newData = [NSMutableData data]; 
[newData appendData:[data subdataWithRange:NSMakeRange(0, start)]]; 
[newData appendData:[data subdataWithRange:NSMakeRange(stopLocation, dataLength-stopLocation)]]; 
NSLog(@"newData: %@", newData); 

的NSLog输出：

ExtractData由：< 00414141 4148475a 3065 5842 4e4e4545 67414141 41414530 30515342 74634451 7961584e 76625141 41412b39 74623239 32414141 41624731 32614751 41414141 41716759 3579366f 474f6373 41414b78 45414143>

newData： 41414141 41514141 41414141 41414141 41>