1.倒序
在ios開發(fā)的過程中，經(jīng)常需要使數(shù)組中的數(shù)據(jù)倒敘排列！比如在tableView顯示數(shù)據(jù)的時候需要使數(shù)據(jù)倒序排列！那么如何解決數(shù)組的倒序排列問題呢？好多開發(fā)的小伙伴可能是便利數(shù)組的下標(biāo)來獲取，但是這種方法如果數(shù)據(jù)很大的情況下程序體驗度會降低 , 這里介紹一個方法，一句話便可以搞定數(shù)組的倒序排序問題！
//
NSMutableArray *temp = [NSMutableArray arrayWithObjects:@"5",@"1",@"4",@"2",nil];
temp = (NSMutableArray *)[[temp reverseObjectEnumerator] allObjects];
2.升序／ 降序
字符串
sortedArrayUsingSelector
//通過自帶的compare方法升序排列
NSMutableArray *array = [[NSMutableArray alloc] initWithObjects:@"5",@"1",@"4",@"2",nil];
[array sortUsingSelector:@selector(compare:)];
//通過倒序的方法進(jìn)行降序排列
NSEnumerator *enumerator = [array reverseObjectEnumerator];
array =[[NSMutableArray alloc]initWithArray: [enumerator allObjects]];
字典
按Key值大小對NSDictionary排序
sortedArrayUsingSelector
NSMutableArray *array = [NSMutableArray arrayWithObjects:
[NSDictionary dictionaryWithObjectsAndKeys:@"Obj0", [NSNumber numberWithInt:0], nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Obj5", [NSNumber numberWithInt:5], nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Obj2", [NSNumber numberWithInt:2], nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Obj3", [NSNumber numberWithInt:3], nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Obj1", [NSNumber numberWithInt:1], nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Obj4", [NSNumber numberWithInt:4], nil], nil];
NSArray *resultArray = [array sortedArrayUsingSelector:@selector(compare:)];
//因為NSDictionary沒有compare的排序比較方法，所以需要我們自己寫一個
- (NSComparisonResult)compare: (NSDictionary *)otherDictionary{
NSDictionary *tempDictionary = (NSDictionary *)self;
NSNumber *number1 = [[tempDictionary allKeys] objectAtIndex:0];
NSNumber *number2 = [[otherDictionary allKeys] objectAtIndex:0];
NSComparisonResult result = [number1 compare:number2];
return result == NSOrderedDescending; // 升序
// return result == NSOrderedAscending; // 降序
}
sortedArrayUsingComparator
NSMutableArray *array = [NSMutableArray arrayWithObjects:
[NSDictionary dictionaryWithObjectsAndKeys:@"Obj0", [NSNumber numberWithInt:0], nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Obj5", [NSNumber numberWithInt:5], nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Obj2", [NSNumber numberWithInt:2], nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Obj3", [NSNumber numberWithInt:3], nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Obj1", [NSNumber numberWithInt:1], nil],
[NSDictionary dictionaryWithObjectsAndKeys:@"Obj4", [NSNumber numberWithInt:4], nil], nil];
// NSArray *resultArray = [array sortedArrayUsingSelector:@selector(compare:)];
NSArray *resultArray = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
NSNumber *number1 = [[obj1 allKeys] objectAtIndex:0];
NSNumber *number2 = [[obj2 allKeys] objectAtIndex:0];
NSComparisonResult result = [number1 compare:number2];
return result == NSOrderedDescending; // 升序
// return result == NSOrderedAscending; // 降序
}];
數(shù)據(jù)模型
sortedArrayUsingDescriptors & sortUsingDescriptors
前者帶返回值，是NSArray的方法，排好序的數(shù)組是返回值中的數(shù)組；
后者不帶返回值，是NSMutableArray的方法，是對當(dāng)前數(shù)組自己排序
接下來根據(jù)一個對象的屬性，排列這個對象
.h
@interface Person : NSObject
@property (nonatomic, retain) NSString *name;
@property (nonatomic, assign) NSInteger age;
@end
.m
@implementation Person
@end
排序方法的實現(xiàn)
Person *person1 = [[Person alloc] init];
person1.name = @"Loki";
person1.age = 25;
Person *person2 = [[Person alloc] init];
person2.name = @"Mike";
person2.age = 22;
Person *person3 = [[Person alloc] init];
person3.name = @"Larry";
person3.age = 33;
NSMutableArray *array = [NSMutableArray arrayWithObjects:person1, person2, person3, nil];
//這里類似KVO的讀取屬性的方法，直接從字符串讀取對象屬性，注意不要寫錯
NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"age" ascending:YES];
//這個數(shù)組保存的是排序好的對象
NSArray *tempArray = [array sortedArrayUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];
for(NSInteger i = 0; i < [tempArray count]; i++)
{
NSLog(@"%@--------%d\n", [[tempArray objectAtIndex:i] name], [[tempArray objectAtIndex:i] age]);
}
//下面是可變數(shù)組的方法
// [array sortUsingDescriptors:[NSArray arrayWithObject:sortDescriptor]];
//
// for(NSInteger i = 0; i < [array count]; i++)
// {
// NSLog(@"%@--------%d\n", [[array objectAtIndex:i] name], [[array objectAtIndex:i] age]);
// }
這里的NSArray中的第一元素表示首先按照這個元素的升序或者降序進(jìn)行排序,對于有重復(fù)項的，再按照第二元素進(jìn)行排序，依次進(jìn)行類推
NSSortDescriptor *sortDescriptor1 = [NSSortDescriptorsortDescriptorWithKey:@"age"ascending:YES];
NSSortDescriptor *sortDescriptor2 = [NSSortDescriptorsortDescriptorWithKey:@"name"ascending:YES];
NSArray *tempArray = [array sortedArrayUsingDescriptors:[NSArrayarrayWithObjects:sortDescriptor1, sortDescriptor2, nil]];