iOS 常用操作

1、判断数组中是否存在某元素

         BOOLisValue = [keyArray containsObject:Q"aaa"];

 

2、把字符串按逗号隔开，并保存到数组：

         NSArray*keyArray=[[NSArray alloc] init];

         keyArray=[@"冬瓜,西瓜,南瓜,苦瓜,丝瓜"componentsSeparatedByString:@","];

 

3、把数组中的取出来，拼成用逗号隔开的字符串：

         NSString*n=[keyArray componentsJoinedByString:@","];

 

4、 NSMutableArray转化成NSArray

 

         NSArray*phoneA=[[NSArray alloc] init];

         NSMutableArray*phoneArrayss=[[NSMutableArray alloc] init];

         phoneA=[phoneArrayssmutableCopy];

 

5、获取本地时间(大写HH获取24小时制的)

 

         NSDateFormatter*formatter = [[NSDateFormatter alloc] init];

         [formattersetDateFormat:@"yyyy-MM-dd HH:mm:ss"];

         NSString*timeStr=[formatter stringFromDate: [NSDate date]];

 

6、去除nsstring中的空格

NSCharacterSet *whitespace =[NSCharacterSet whitespaceAndNewlineCharacterSet ];

NSString * username = [mUsernameField stringValue];

username = [usernamestringByTrimmingCharactersInSet :whitespace];

 

7、需要判断的地方：

  IsNetworking *IsNetWork = [[IsNetworking alloc] init];

   BOOL isNets=[IsNetWork isNetworkReachable];

   if(isNets==NO){

         //没有网络

    }

   else{

         //有网络

    }

 

8、追加字符：

         NSMutableString*string = [[NSMutableString alloc] init];

         string=@“你好”；

         [stringappendFormat:@"中国"];

 

9、字符串替换：把info中所有的<都替换成#

         NSString*stroneIntro=[info stringByReplacingOccurrencesOfString:@"<"

withString:@"#"];

 

10、字符串比较：

         BoolIsTrue=[@"Nob"isEqualToString:@"Mob"]

 

11、不考虑大小写比较字符串

         NSString*astring01 = @"this is a String!";

         NSString*astring02 = @"This is a String!";

         BOOLresult = [astring01 caseInsensitiveCompare:astring02] = =NSOrderedSame;

 

12、改变字符串的大小写

         NSString*string1 = @"A String";

         NSString*string2 = @"String";

         NSLog(@"string1:%@",[string1uppercaseString]);//大写

         NSLog(@"string2:%@",[string2lowercaseString]);//小写

         NSLog(@"string2:%@",[string2capitalizedString]);//首字母大小

 

 

13、在串中搜索子串

         NSString*string1 = @"This is a string";

         NSString*string2 = @"string";

         NSRangerange = [string1 rangeOfString:string2];

         intlocation = range.location;

         intleight = range.length;

         NSString*astring = [[NSString alloc] initWithString:                

[NSStringstringWithFormat:@"Location:%i,Leight:%i",location,leight]];

         NSLog(@"astring:%@",astring);

         [astringrelease];

 

 

 

14、 抽取子串

 

//-substringToIndex: 从字符串的开头一直截取到指定的位置，但不包括该位置的字符

         NSString*string1 = @"This is a string";

         NSString*string2 = [string1 substringToIndex:3];

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

 

 

//-substringFromIndex:以指定位置开始（包括指定位置的字符），并包括之后的全部字符

         NSString*string1 = @"This is a string";

         NSString*string2 = [string1substringFromIndex:3];

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

 

//-substringWithRange: //按照所给出的位置，长度，任意地从字符串中截取子串

         NSString*string1 = @"This is a string";

         NSString*string2 = [string1 substringWithRange:NSMakeRange(0,4)];

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

 

 

 

15、判断字符串内是否还包含别的字符串(前缀，后缀)

         //01：检查字符串是否以另一个字符串开头- (BOOL) hasPrefix: (NSString *)aString;

         NSString*String1 = @"NSStringInformation.txt";

         [String1hasPrefix:@"NSString"] = = 1 ? NSLog(@"YES") :NSLog(@"NO");

         [String1hasSuffix:@".txt"] = = 1 ? NSLog(@"YES"): NSLog(@"NO");