[oc学习笔记]数组的遍历和排序

//数组的遍历(可变数组举例)
//for遍历
NSMutableArray *aa = [NSMutableArray array];
[aa addObjectsFromArray:@[@"ss",@"ddd",@"sad"]];
for (int i = 0;  i < aa.count; i++) {
NSLog(@"%@",[aa objectAtIndex:i]);
}
//快速遍历
for (id obj in aa) {
NSLog(@"%@",obj);
}
//代码块遍历
// obj是对象 idx是下标 stop是停止标志
[aa enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
NSLog(@"%@",obj);
NSLog(@"%@",[aa objectAtIndex:idx]);
}];
//迭代器遍历
//将数组元素存放进迭代器
NSEnumerator *en = [aa objectEnumerator];
id obj = nil;//创建一个对象接受返回对象
while (obj = [en nextObject]) {
NSLog(@"%@",obj);
}
//反向迭代器遍历
NSEnumerator *en1 = [aa reverseObjectEnumerator];
id obj1 = nil;
while (obj1 = [en1 nextObject]) {
NSLog(@"%@",obj1);
}

//排序(可变数组举例)
//可变数组排序的方法无返回值 不可变数组的排序有返回值
//选择器排序
//compare方法尽限于比较元素是字符时 ，如有另外的比较 请另写比较方法 返回值（NSComparisonResult）
[aa sortUsingSelector:@selector(compare:)];
//代码块排序
//根据实际情况写判断方法
[aa sortUsingComparator:^NSComparisonResult(id obj1, id obj2) {
return [obj1 compare:obj2];
}];
//比较描述器排序
//对多个条件进行排序比较便利
Person *p1 = [[Person alloc]init];
p1.name = @"ss";
p1.age = @"16";

Person *p2 = [[Person alloc]init];
p2.name = @"dd";
p2.age = @"14";

Person *p3 = [[Person alloc]init];
p3.name = @"hh";
p3.age = @"22";

Person *p4 = [[Person alloc]init];
p4.name = @"hh";
p4.age = @"19";
NSMutableArray *sss = [NSMutableArray arrayWithObjects:p1,p2,p3,p4,nil];
NSSortDescriptor *sort1 = [NSSortDescriptor sortDescriptorWithKey:@"name" ascending:YES];
NSSortDescriptor *sort2 = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:YES];
NSArray *s = @[sort1,sort2];
[sss sortUsingDescriptors:s];
NSLog(@"%@",sss);

#import <Foundation/Foundation.h>

@interface Person : NSObject
@property (nonatomic,strong)NSString *name;
@property (nonatomic,strong)NSString *age;
@end

#import "Person.h"

@implementation Person
- (NSString *)description
{
return [NSString stringWithFormat:@"%@ %@", _name,_age];
}
@end

2015-06-01 17:37:55.984 Array[2030:140148] ss
2015-06-01 17:37:55.985 Array[2030:140148] ddd
2015-06-01 17:37:55.985 Array[2030:140148] sad
2015-06-01 17:37:55.986 Array[2030:140148] ss
2015-06-01 17:37:55.986 Array[2030:140148] ddd
2015-06-01 17:37:55.986 Array[2030:140148] sad
2015-06-01 17:37:55.986 Array[2030:140148] ss
2015-06-01 17:37:55.986 Array[2030:140148] ss
2015-06-01 17:37:55.986 Array[2030:140148] ddd
2015-06-01 17:37:55.987 Array[2030:140148] ddd
2015-06-01 17:37:55.987 Array[2030:140148] sad
2015-06-01 17:37:55.987 Array[2030:140148] sad
2015-06-01 17:37:55.992 Array[2030:140148] ss
2015-06-01 17:37:55.992 Array[2030:140148] ddd
2015-06-01 17:37:55.992 Array[2030:140148] sad
2015-06-01 17:37:55.992 Array[2030:140148] sad
2015-06-01 17:37:55.992 Array[2030:140148] ddd
2015-06-01 17:37:55.993 Array[2030:140148] ss
2015-06-01 17:37:55.993 Array[2030:140148] (
"dd 14",
"hh 19",
"hh 22",
"ss 16"
)