NSNumber
1.定義基本數據類型
char a = 'f';
int b = 5;
short c = 20;
long d = 100;
float e = 2.5;
double f = 225.214;
BOOL isTrue = YES;
2.將基本數據類型轉化爲NSNumber類型的對象
NSNumber *a1 = [NSNumber numberWithChar:a];
NSNumber *b1 = [NSNumber numberWithInt:b];
NSNumber *c1 = [NSNumber numberWithShort:c];
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NSNumber *isTrue1 = [NSNumber numberWithBool:isTrue];
將對象存入數組中
NSArray *arr = [NSArray arrayWithObjects:a1,b1,c1,d1,e1,f1,isTrue1,nil];
NSLog(@"%@",arr);
3.將NSNumber類型的對象轉化爲基本數據類型
char a2 = [a1 charValue];
int b2 = [b1 intValue];
4NSNumber類型的比較
NSLog(@"%ld",[a1 compare:b1]); //升序爲-1,降序爲1,相等爲0;
NSArray
NSLog(@"%lu",count);
//(1).獲取指定下標對應的元素
NSString *str = [arr2 objectAtIndex:1];
NSLog(@"%@",str);
//(2).獲取數組中的第一個元素
//firstObject 與 lastObject 好在當數組元素爲空時,會返回nil 而objectAtIndex則會造成程序crash . index 0 beyond bounds of empty array 數組下標越界.
NSString *str1 = [arr2 firstObject];
NSLog(@"%@",str1);
//(3).獲取數組中的最後一個元素
NSString *str2 = [arr2 lastObject];
NSLog(@"%@",str2);
4.獲取對象在數組中的索引值
NSUInteger index = [arr2 indexOfObject:@"dd"];
NSLog(@"%lu",index);
5.判斷是否包含某個對象
BOOL isExist = [arr2 containsObject:@"Frank"];
NSLog(@"iseExist = %d",isExist);
NSArray *sortArr = [arr2 sortedArrayUsingSelector:@selector(compare:)];
NSLog(@"%@",sortArr);
// for (int i = 0; i < [arr2 count]; i++) {
// NSString *str = [arr2 objectAtIndex:i];
// NSLog(@"%@",str);
// }
for (NSString *str in arr2) {
NSLog(@"%@",str);
}
}
// 數組元素類型 起一個對象的名字(自己擬定)
// for (<#type *object#> in <#collection#>) {
// <#statements#> 集合(也就是大容器,數組,字典,或者集合)
// }
// forin 快速枚舉(遍歷),用於將集合中的元素便利出來
下面舉一個例子
Book *book1 = [[Book alloc]initWithName:@"IOS初級1" author:@"Frank" price:1];
Book *book2 = [[Book alloc]initWithName:@"IOS初級2" author:@"Frank" price:2];
Book *book3 = [[Book alloc]initWithName:@"IOS初級3" author:@"Frank" price:3];
NSMutableArray *arr = [[NSMutableArray alloc]initWithObjects:book1,book2,book3, nil];
Book *book4 = [[Book alloc]initWithName:@"IOS初級4" author:@"Frank" price:4];
[arr addObject:book4];
[arr removeObjectAtIndex:0];
5.通過書名查找書
for (Book *BOOK in arr) {
//獲取到數組中的元素,然後對比名字,如果相同就輸出名字
if ([[BOOK name]
isEqualToString:@"IOS初級3"]) {
[BOOK setPrice:1000];
NSLog(@"%@",[BOOK name]);
NSLog(@"查找成功");
}
}
NSLog(@"%.2f",[book3 price]);
for (Book *book in arr) {
NSLog(@"%@",book);
}