[Oc learning notes] array traversal and sorting, oc learning notes

[Oc learning notes] array traversal and sorting, oc learning notes

1 // array traversal (variable array example) 2 // for traversal 3 NSMutableArray * aa = [NSMutableArray array]; 4 [aa addObjectsFromArray: @ [@ "ss ", @ "ddd", @ "sad"]; 5 for (int I = 0; I <aa. count; I ++) {6 NSLog (@ "% @", [aa objectAtIndex: I]); 7} 8 // fast traversal 9 for (id obj in aa) {10 NSLog (@ "% @", obj); 11} 12 // code block traversal 13 // obj is the object idx is the subscript stop is the stop sign 14 [aa enumerateObjectsUsingBlock: ^ (id obj, NSUInteger idx, BOOL * stop) {15 NSLog (@ "% @", obj); 16 NSLog (@ "% @", [aa objectAtIndex: idx]); 17}]; 18 // iterator traversal 19 // store array elements into iterator 20 NSEnumerator * en = [aa objectEnumerator]; 21 id obj = nil; // create an object to accept the returned object 22 while (obj = [en nextObject]) {23 NSLog (@ "% @", obj ); 24} 25 // The Reverse iterator traverses 26 NSEnumerator * en1 = [aa reverseObjectEnumerator]; 27 id obj1 = nil; 28 while (obj1 = [en1 nextObject]) {29 NSLog (@ "% @", obj1); 30} 31 32 33 // sort (variable array example) 34 // variable array sorting method no return value immutable array sorting return value 35 // selector sorting 36 // when the comparison element is a character, if there is another comparison, please write another comparison method return value (NSComparisonResult) 37 [aa sortUsingSelector: @ selector (compare :)]; 38 // code block sorting 39 // write judgment method based on actual conditions 40 [aa sortUsingComparator: ^ NSComparisonResult (id obj1, id obj2) {41 return [obj1 compare: obj2]; 42}]; 43 // The comparison descriptor sorts 44 // It is easier to sort multiple conditions 45 Person * p1 = [[Person alloc] init]; 46 p1.name = @ "ss"; 47 p1.age = @ "16"; 48 49 Person * p2 = [[Person alloc] init]; 50 p2.name = @ "dd "; 51 p2.age = @ "14"; 52 53 Person * p3 = [[Person alloc] init]; 54 p3.name = @ "hh"; 55 p3.age = @ "22 "; 56 57 Person * p4 = [[Person alloc] init]; 58 p4.name = @ "hh"; 59 p4.age = @ "19"; 60 NSMutableArray * sss = [NSMutableArray arrayWithObjects: p1, p2, p3, p4, nil]; 61 NSSortDescriptor * sort1 = [NSSortDescriptor sortDescriptorWithKey: @ "name" ascending: YES]; 62 NSSortDescriptor * sort2 = [NSSortDescriptor: @ "age" ascending: YES]; 63 NSArray * s = @ [sort1, sort2]; 64 [sss sortUsingDescriptors: s]; 65 NSLog (@ "% @", sss );

Person. h

1 #import <Foundation/Foundation.h>2 3 @interface Person : NSObject4 @property (nonatomic,strong)NSString *name;5 @property (nonatomic,strong)NSString *age;6 @end

Person. m

1 #import "Person.h"2 3 @implementation Person4 - (NSString *)description5 {6     return [NSString stringWithFormat:@"%@ %@", _name,_age];7 }8 @end

Running result analysis:

2015-06-01 17:37:55.984 Array[2030:140148] ss2015-06-01 17:37:55.985 Array[2030:140148] ddd2015-06-01 17:37:55.985 Array[2030:140148] sad2015-06-01 17:37:55.986 Array[2030:140148] ss2015-06-01 17:37:55.986 Array[2030:140148] ddd2015-06-01 17:37:55.986 Array[2030:140148] sad2015-06-01 17:37:55.986 Array[2030:140148] ss2015-06-01 17:37:55.986 Array[2030:140148] ss2015-06-01 17:37:55.986 Array[2030:140148] ddd2015-06-01 17:37:55.987 Array[2030:140148] ddd2015-06-01 17:37:55.987 Array[2030:140148] sad2015-06-01 17:37:55.987 Array[2030:140148] sad2015-06-01 17:37:55.992 Array[2030:140148] ss2015-06-01 17:37:55.992 Array[2030:140148] ddd2015-06-01 17:37:55.992 Array[2030:140148] sad2015-06-01 17:37:55.992 Array[2030:140148] sad2015-06-01 17:37:55.992 Array[2030:140148] ddd2015-06-01 17:37:55.993 Array[2030:140148] ss2015-06-01 17:37:55.993 Array[2030:140148] (    "dd 14",    "hh 19",    "hh 22",    "ss 16")