API之NSString的常见用法

/*

//长度

NSString *string = [[NSString alloc]

initWithFormat:@"sDGijkhajkhKHklhDSHJgDst"];

// NSLog(@"%lu", [string length]);

//- (unichar)characterAtIndex:

(NSUInteger)index; //输出某个下标指定位置的字符

NSString *s = [[NSString

alloc]initWithFormat:@"abcKJGHJ"];

NSLog(@"%c", [s characterAtIndex:2]);

// - (NSString *)substringFromIndex:

(NSUInteger)from; //输出从index下标开始后⾯面的所有字符串

NSLog(@"%@", [string substringFromIndex:4]);

// - (NSString *)substringToIndex:

(NSUInteger)to; //从字符串开始位置到index下标位置逐⼀一输出

NSLog(@"%@", [string substringToIndex:5]);

// - (NSString *)substringWithRange:

(NSRange)range; //输出range范围内的字符串

NSLog(@"%@", [string substringWithRange:NSMakeRange(2, 5)]);

// - (NSComparisonResult)compare:(NSString*)string; //后⾯面与前⾯面相⽐比较

if ([string compare:s] == -1) {

NSLog(@"升序");

} else if ([string compare:s] == 1) {

NSLog(@"降序");

} else {

NSLog(@"相等");

}

// - (NSComparisonResult)caseInsensitiveCompare:

(NSString *)string; //不区分大小写的比较

if ([string caseInsensitiveCompare:s]) {

NSLog(@"yes");

} else {

NSLog(@"no");

}

// - (NSComparisonResult)localizedCompare:

(NSString *)string; //局部比较

if ([s localizedCompare:string]) {

NSLog(@"yes");

} else {

NSLog(@"no");

}

// -

(NSComparisonResult)localizedCaseInsensitiveCompare:(NSString *)string; //不区分大小写比较前一个字符串是否包含后一个字符串

if ([string

localizedCaseInsensitiveContainsString:s]) {

NSLog(@"yes");

} else {

NSLog(@"no");

}

// - (NSComparisonResult)localizedStandardCompare:(NSString *)string //标准比较

if ([string localizedStandardCompare:s]) {

NSLog(@"yes");

} else {

NSLog(@"no");

}

// - (BOOL)isEqualToString:(NSString*)aString; //判断两个字符串是否相等

if ([string isEqualTo:s]) {

NSLog(@"1");

} else {

NSLog(@"0");

}

// - (BOOL)hasPrefix:(NSString *)aString; //前缀

if ([string hasPrefix:@"sD"]) {

NSLog(@"yes");

} else {

NSLog(@"no");

}

// - (BOOL)hasSuffix:(NSString *)aString; //后缀

if ([string hasSuffix:@"dst"]) {

NSLog(@"yes");

} else {

NSLog(@"no");

}

*/

/*

// - (BOOL)containsString:(NSString *)aString //是否包含字符串

if ([string containsString:@"a"]) {

NSLog(@"yes");

} else {

NSLog(@"no");

}

// - (BOOL)localizedCaseInsensitiveContainsString:

(NSString *)aString //不区分大小写是否包含字符串

if ([string containsString:@"D"]) {

NSLog(@"yes");

} else {

NSLog(@"no");

}

// - (NSRange)rangeOfString:(NSString

*)aString; //输出字符串的坐标

NSRange r1 = [string rangeOfString:@"a"];

NSLog(@"{%lu, %lu}", r1.location, r1.length);

// - (NSRange)rangeOfCharacterFromSet:

(NSCharacterSet *)aSet;

NSRange r3 = [string

rangeOfComposedCharacterSequenceAtIndex:3];

NSLog(@"{%lu, %lu}", r3.location, r3.length);

// - (NSString *)stringByAppendingString:(NSString*)aString; //拼接字符串

// - (NSString *)stringByAppendingFormat:(NSString*)format, ... //格式化拼接字符串

// NSLog(@"%@", string);

*/

// - (NSArray *)componentsSeparatedByString:(NSString *)separator;

NSArray *array= [[NSArray alloc]

initWithObjects:@"123", @"sdf", @"456", @"dfg", nil];

[array componentsJoinedByString:@"s"];

NSLog(@"%@", array);

//

// NSLog(@"%@", [string uppercaseString]); //大写输出

// NSLog(@"%@", [string lowercaseString]); //小写输出

// NSLog(@"%@", [string capitalizedString]); //首字母大写

//

// NSString * str = [[NSString alloc]

initWithFormat:@"qwerrtyyu"];

// NSLog(@"%@", [str description]);

// */

/*

// @property (readonly) NSUInteger hash; 将字母转换成对应的哈希值

NSLog(@"%lu", [@"f" hash]);

*/

//搜索条件

/*

enum{

NSCaseInsensitiveSearch = 1,//不区分大小写比较

NSLiteralSearch = 2,//区分大小写比较

NSBackwardsSearch = 4,//从字符串末尾开始搜索

NSAnchoredSearch = 8,//搜索限制范围的字符串

NSNumbericSearch = 64//按照字符串里的数字为依据，算出顺序。例如 Foo2.txt < Foo7.txt < Foo25.txt

//以下定义高于mac os 10.5 或者⾼高于iphone 2.0 可用

NSDiacriticInsensitiveSearch = 128,//忽略 "-"符号的比较

NSWidthInsensitiveSearch = 256,//忽略字符串的⻓长度，比较出结果

NSForcedOrderingSearch = 512//忽略不区分大小写比较的选项，并强制返回 NSOrderedAscending 或者NSOrderedDescending

//以下定义⾼高于iphone 3.2 可⽤用,

NSRegularExpressionSearch = 1024//只能应用于

rangeOfString:...,

stringByReplacingOccurrencesOfString:...和replaceOccurrencesOfString:... 方法。使用通用兼容的比较方法，如果设置此项，可以去掉 NSCaseInsensitiveSearch 和

NSAnchoredSearch

}*/

/*

//可变字符串

NSMutableString *mString = [[NSMutableString alloc] initWithFormat:@"师徒四人妖魔鬼怪"];

[mString insertString:@"西天取经" atIndex:4];

NSLog(@"%@", mString);

[mString deleteCharactersInRange:NSMakeRange(4,4)];

NSLog(@"%@", mString);

[mString appendFormat:@"纵横天地间"];

NSLog(@"%@", mString);

[mString appendString:@"无人能管"];

NSLog(@"%@", mString);

//- (NSMutableString *)initWithCapacity:

(NSUInteger)capacity;

//带容量的初始化

//+ (NSMutableString *)stringWithCapacity:

(NSUInteger)capacity;

//带容量的便利构造器

[mString replaceOccurrencesOfString:@"纵横天地间"

withString:@"从东土大唐到西天圣地"

options:NSBackwardsSearch range:NSMakeRange(8, 8)];

NSLog(@"%@", mString);

//估计一下你要申请多少空间,相当于一个单位

// NSMutableString *string2 =

[[NSMutableString alloc] initWithCapacity:10];

// [string2 appendString:@"haha"];

// NSLog(@"%@", string2);

//

// NSMutableString * string3 =

[[NSMutableString alloc]

initWithFormat:@"xxxxxxx.pcg"];

// if ([string3 hasSuffix:@"png"]) {

// NSRange range = [string3

rangeOfString:@"png"];

// [string3 replaceCharactersInRange:range

withString:@"jpg"];

// } else {

// [string3 appendString:@"jpg"];

// }

// NSLog(@"%@", string3);

*/