linq(like c#) to objective-c .
make an array first:
NSArray *sexs=[NSArray arrayWithObjects:@"f",@"m", nil];
NSArray *myArray = [NSArray arrayWithLength:10 andObject:^id(NSInteger currentIndex, NSInteger length) {
Student *s=[Student new];
s.name=[NSString stringWithFormat:@"s%d",currentIndex];
s.age=arc4random()%5+18;
s.sex=[sexs objectAtIndex:arc4random()%2];
s.ID=arc4random()%1000+1000;
return s;
}];
myArray:
(
" id: 1919 - name: s0 - age: 20 - sex: f ",
" id: 1122 - name: s1 - age: 21 - sex: m ",
" id: 1439 - name: s2 - age: 18 - sex: f ",
" id: 1697 - name: s3 - age: 21 - sex: m ",
" id: 1817 - name: s4 - age: 20 - sex: f ",
" id: 1499 - name: s5 - age: 19 - sex: m ",
" id: 1757 - name: s6 - age: 20 - sex: f ",
" id: 1848 - name: s7 - age: 19 - sex: m ",
" id: 1857 - name: s8 - age: 20 - sex: m ",
" id: 1912 - name: s9 - age: 22 - sex: f "
)get student's name list like this :
NSArray *nameList=[myArray select:^id(Student* target) {
return target.name;
}];
nameList:
(
s0,
s1,
s2,
s3,
s4,
s5,
s6,
s7,
s8,
s9
)
get students where age > 20:
NSArray *studentList=[myArray where:^BOOL(Student* target) {
return target.age>20;
}];
studentList:
(
" id: 1122 - name: s1 - age: 21 - sex: m ",
" id: 1697 - name: s3 - age: 21 - sex: m ",
" id: 1912 - name: s9 - age: 22 - sex: f "
)
get students where age >= 20 and group by sex:
NSDictionary *studentDic=[myArray where:^BOOL(Student* target) {
return target.age>=20;
}] groupBy:^id(Student* obj) {
return obj.sex;
}];
studentDic:
{
f = (
" id: 1919 - name: s0 - age: 20 - sex: f ",
" id: 1817 - name: s4 - age: 20 - sex: f ",
" id: 1757 - name: s6 - age: 20 - sex: f ",
" id: 1912 - name: s9 - age: 22 - sex: f "
);
m = (
" id: 1122 - name: s1 - age: 21 - sex: m ",
" id: 1697 - name: s3 - age: 21 - sex: m ",
" id: 1857 - name: s8 - age: 20 - sex: m "
);
}