最近闲来无聊，做 iOS也很长时间了，心想是时候开始记录自己的一点点经验了。那么今天就先来总结一下OC中对NSString的处理吧。
一、对于字符串的操作
1.截取字符串
NSString*string =@"abcdefghijklmn";
string = [string substringToIndex:7];//截取掉下标7之后的字符串
NSLog(@"截取的值为：%@",string);//输出结果为:ijkimn
NSString*string =@"abcdefghijklmn";
[string substringFromIndex:2];//截取掉下标2之前的字符串
NSLog(@"截取的值为：%@",string);//输出结果为:abc
NSString*string =@"abcdefghijklmn";
string = [string substringWithRange:NSMakeRange(4,2)];//截取下标为4范围为2的字符串
NSLog(@"截取的值为：%@",string);//输出结果为:ef
2.匹配字符串
NSString*string =@"abcdefghijklmn";
NSRange range = [string rangeOfString:@"f"];//匹配得到的下标
NSLog(@"range:%@",NSStringFromRange(range));//输出结果为range:{5,1}
string = [string substringWithRange:range];//截取范围类的字符串
NSLog(@"截取的值为：%@",string);//输出结果为:f
3.分隔字符串
NSString*string =@"abcdeAfghijk";
NSArray *array = [string componentsSeparatedByString:@"A"]; //从字符A中分隔成2个元素的数组
NSLog(@"array:%@",array); //结果是abcde和fghijk
4.替换字符串
NSString*string = @"abcdefghljklmn";
string = [string stringByReplacingOccurrencesOfString:@"abc" withString:@"123"];
NSLog(@"string:%@",string);//结果为:123defghljklmn
二、有时候我们需要对于字符串是否为空进行判断
在网上搜集到的判断string为空的方法
string.length == 0 || [string isEqualToString:@""] || string == nil || string == NULL || [string isEqual:[NSNull null]] || [string isEqualTostring:@“(null)”] || [string isEqual:@"(null)"] || [string isKindOfClass:[NSNull class]] || [[string stringByTrimmingCharactersInSet:[NSCharacterSetwhitespaceAndNewlineCharacterSet]] length]==0
三、字符串可以比较大小
NSString*a =@"asd";
NSString*b =@"dfs";
NSComparisonResultresult = [stra compare:strb];
if(result ==NSOrderedSame) {
//NSLog(@"a = b");
}elseif(result ==NSOrderedAscending) {
//NSLog(@"a < b");
}else{
//NSLog(@"a > b");
}
三、常用扩展功能(类别扩展)
1.md5
- (NSString*)md5HexDigest
{
constchar* str = [selfUTF8String];unsignedcharresult[CC_MD5_DIGEST_LENGTH];
CC_MD5(str, strlen(str), result);
NSMutableString*ret = [NSMutableStringstringWithCapacity:CC_MD5_DIGEST_LENGTH];
for(int i =0; i<CC_MD5_DIGEST_LENGTH; i++{
[ret appendFormat:@"%02X",result[i]];
}returnret;
}
2.urlEncode
- (NSString*)stringEncode {NSString*encodedString = (NSString*)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)self,NULL,CFSTR(":/?#[]@!$ &'()*+,;=\"<>%{}|\\^~`"), kCFStringEncodingUTF8));returnencodedString;
}
- (NSString*)stringDecode {NSString*result = [(NSString*)selfstringByReplacingOccurrencesOfString:@"+"withString:@" "];
result = [result stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];returnresult;
}
3.sizeFromFont
- (CGSize)boundingRectWithSize:(CGSize)size
withTextFont:(UIFont*)font {if([selfisEqualToString:@""]) {returnCGSizeMake(0,0);
}NSMutableParagraphStyle*paragraphStyle = [[NSMutableParagraphStylealloc] init];
paragraphStyle.lineBreakMode =NSLineBreakByWordWrapping;
paragraphStyle.lineSpacing =0;NSDictionary*attributes = @{NSFontAttributeName:font,NSParagraphStyleAttributeName:paragraphStyle.copy};return[selfboundingRectWithSize:size options:NSStringDrawingUsesLineFragmentOriginattributes:attributes context:nil].size;
}
4.是否是邮箱格式
- (BOOL)isEmail
{
NSString*emailRegEx =@"(?:[a-z0-9!#$%\\&'*+/=?\\^_`{|}~-]+(?:\\.[a-z0-9!#$%\\&'*+/=?\\^_`{|}"@"~-]+)*|\"(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21\\x23-\\x5b\\x5d-\\"@"x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])*\")@(?:(?:[a-z0-9](?:[a-"@"z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\\[(?:(?:25[0-5"@"]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-"@"9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21"@"-\\x5a\\x53-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])+)\\])";
NSPredicate*regExPredicate = [NSPredicatepredicateWithFormat:@"SELF MATCHES %@", emailRegEx];return[regExPredicate evaluateWithObject:[selflowercaseString]];
}
5.Base64
- (NSString*)base64 {
// Create NSData object
NSData*nsdata = [selfdataUsingEncoding:NSUTF8StringEncoding];
// Get NSString from NSData object in Base64
NSString*base64Encoded = [nsdata base64EncodedStringWithOptions:0];// Print the Base64 encoded stringreturnbase64Encoded;
}
- (NSString*)base64Decoded {
// NSData from the Base64 encoded str
NSData*nsdataFromBase64String = [[NSDataalloc] initWithBase64EncodedString:selfoptions:0];
// Decoded NSString from the NSData
NSString*base64Decoded = [[NSStringalloc] initWithData:nsdataFromBase64String encoding:NSUTF8StringEncoding];returnbase64Decoded;
}
就先到这里吧，如果有什么地方有欠妥的地方希望能有人指出来，先拜谢了
