1、使用NSString自定義的方法

NSString* teststr = @"aaaak$kbbbbk$kcccc";
NSLog(@"%@", teststr);
NSMutableString* nsstrmutable = [[NSMutableString alloc] initWithString:teststr];
[nsstrmutable replaceOccurrencesOfString:@"k$k" withString:@"TTT" options:NSCaseInsensitiveSearch range:NSMakeRange(0, nsstrmutable.length
 
)];
NSLog(@"%@", nsstrmutable);

輸出：

2015-12-14 10:32:45.070 delcmd[823:285871] aaaak$kbbbbk$kcccc
2015-12-14 10:32:45.073 delcmd[823:285871] aaaaTTTbbbbTTTcccc

2、使用CFString

NSString* teststr = @"aaaak$kbbbbk$kcccc";
NSLog(@"%@", teststr);

CFStringRef cfstr = (__bridge CFStringRef) teststr;
CFMutableStringRef cfstrmutable = CFStringCreateMutableCopy(NULL
 
, CFStringGetLength(cfstr), cfstr);
CFStringFindAndReplace(cfstrmutable, CFSTR("k$k"), CFSTR("TTT"), CFRangeMake(0, CFStringGetLength(cfstrmutable)), kCFCompareCaseInsensitive);
NSString* str = (__bridge NSString*) cfstrmutable;
CFRelease(cfstrmutable);
NSLog(@"%@", str);

輸出

2015-12-14 10:32:45.070 delcmd
 
[823:285871] aaaak$kbbbbk$kcccc
2015-12-14 10:32:45.073 delcmd[823:285871] aaaaTTTbbbbTTTcccc

3、使用正則 匹配替換

NSString* teststr = @"aaaak$kbbbbk$kcccc";
NSLog(@"%@", teststr);

NSError* error = nil;
NSRegularExpression* exp = [[NSRegularExpression alloc] initWithPattern:@"(.*?)k\\$k(.*?)" options:NSRegularExpressionCaseInsensitive error:&error];
NSString* expstr = [exp stringByReplacingMatchesInString:teststr options:0 range:NSMakeRange(0, teststr.length) withTemplate:@"$1TTT$2"];
NSLog(@"%@", expstr);

輸出

2015-12-14 10:32:45.070 delcmd[823:285871] aaaak$kbbbbk$kcccc
2015-12-14 10:32:45.073 delcmd[823:285871] aaaaTTTbbbbTTTcccc