OC NSString(字符串)

OC NSString(字符串)

---

多行文字字面量

NSString * string = @"abC"
        			@"DEF"
        			@"hjk"
        			@"uuiop";

NSRange的使用

typedef struct _NSRange {
	NSUInteger location;
	NSUInteger length;
} NSRange;

//定义：
NSRange range = {2,2};
//使用：
NSString * newString =  [string substringWithRange:range]；

常用方法

在A字符串中查找B字符串，返回B字符串在A中的位置

- (NSRange)rangeOfString:(NSString *)searchString;

//举例：
NSRange range = [string rangeOfString:@"gs"];

if (range.length == 0) {
	NSLog(@"没有找到liu");
}
if (range.location == NSNotFound) {
	NSLog(@"没有找到liu");
}

NSCaseInsensitiveSearch 忽略大小写

[string rangeOfString:@"ha" options:NSCaseInsensitiveSearch]

不可变字符串常用方法

带占位符的拼接字符串方法 stringByAppendingFormat

NSString * newString = [string stringByAppendingFormat:@"def%d",12];

拼接字符串方法 stringByAppendingString

NSString * newString = [string stringByAppendingString:@"opiuuoo"];

填充字符串 stringByPaddingToLength: withString: startingAtIndex:

NSString * newstring = [string stringByPaddingToLength:10 withString:@"123" startingAtIndex:2];

分割字符串 componentsSeparatedByString

NSArray * array = [string componentsSeparatedByString:@"-"];

通过数组合并字符串 componentsJoinedByString

NSString * string = [array componentsJoinedByString:@"-"];

给字符串前后去空格 stringByTrimmingCharactersInSet

NSString * string = [string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

替换字符串 stringByReplacingOccurrencesOfString

NSString * newString = [string stringByReplacingOccurrencesOfString:@"hu" withString:@" "];

根据range替换字符串 stringByReplacingCharactersInRange:

		NSRange range = {4,4};
        string = [string stringByReplacingCharactersInRange:range withString:@"shifan"];

大写字母转小写 lowercaseString

NSString * newString2 = [string2 lowercaseString];

小写字母转大写 uppercaseString

NSString * newString1 = [string1 uppercaseString];

首字母大写 capitalizedString

NSString * newString2 = [string2 capitalizedString];

字符串比较函数 compare:

NSComparisonResult rs = [string1 compare:string2];

忽略大小比较字符串 caseInsensitiveCompare:

NSComparisonResult rs = [string1 caseInsensitiveCompare:string2];

if (rs == NSOrderedAscending) {
	NSLog(@"string1 < string2");
} else if (rs == NSOrderedSame) {
	NSLog(@"string1 = string2");
} else {
	NSLog(@"string1 > string2");
}

字符串转基本数据类型

int num = [string intValue];
double numd = [string doubleValue];
//还有： floatValue，integerValue，longLongValue，boolValue

可变字符串NSMutableString

初始化方法

NSMutableString * string = [[NSMutableString alloc] initWithCapacity:5];
NSMutableString * s = [[NSMutableString alloc] initWithString:@"ab"];

追加方法

[s appendFormat:@"%d",1];
[s appendString:@"123"];

插入方法

[string insertString:@"90" atIndex:2];

替换方法

[string replaceCharactersInRange:range withString:@"jj"];

删除方法

[string deleteCharactersInRange:range];

不可变字符串转可变字符串（重置字符串）

[string setString:str];