1.建議使用 [NSString stringWithxxxxx:@""];這樣不用自己管理內(nèi)存
2.將字符串中的字符全部變?yōu)榇髮?xiě):[@"Hello World" uppercaseString]; @"HELLO WORLD"
3.將字符串的的字符全部變?yōu)樾?xiě):[@"Hello World" lowercaseString];
@"hello world"
4.將字符串的首字母轉(zhuǎn)換為大些:[@"Hello world" capitaliaedString];
@"Hello World"
5.判斷是否相等[@"abc" isEqualToString:@"aBc"];
6.比較兩個(gè)字符串:
NSComparisonResult result = [@"abc" compare:@"aBc"];
三種輸出：NSOrderedDescending NSOrderedSame NSOrderedDescending
7.判斷字符串是否以啥開(kāi)頭[@"abcedfg" hasPrefix"@"ab"];
8.判斷字符串是否以啥結(jié)尾[@"abcdefg" hasSuffix:@"fg"];
9.判斷字符串中是否有啥字符串[@"abcedfg" rangeOfString:@"cde"];
10.[@"abcedfg" substringFromIndex:3];//從第三個(gè)索引開(kāi)始（包含第三個(gè)索）截取到最后一位
11.[@"abcdefg" substringToIndex:3];//從0開(kāi)始截取到第三個(gè)索引(不包括第三個(gè)索引)
12.NSString *str = @"12.abcd.12d"; 
    NSArray *array = [str componentSeoaratedByString:@"."];
    array = [@"12", @"abcd",@"12d"];
13.類型轉(zhuǎn)換
     NSLog(@"%i", [@"12" intValue]);
14.計(jì)算字符串長(zhǎng)度
     NSLog([@"Hello World, 世界你好" length]);
15.取出指定的字符串
     NSLog([@"abc" characterAtIndex:0]);
16.OC ---> C
    const char *s =  [@"abc" UTF8String];
17.追加字符串
    [str appendString:@"abc"];
18.[str appendFormat@"我的年齡是%i"， 18]；
19.替換字符串
    NSRange range = [str rangeOfString"@"dear"];
    [str replaceCharactersInRange:range withString:@"Honey"];
20.插入字符串
    [str insertString:@"My name is Sunjian." atIndex:12];
21.刪除指定字符串：
    [str deleteCharactersInRange:[str rangeOfString@"My name is Sunjian."]];