//
创建一个block
//
1.返回值
//
2.使用‘^’标记一个Block，并写出Block变量
//
3.确定Block参数列表，参数名可以省略
// 4.‘^’
//
5.参数列表
//
6.主题部分，‘{}；’
//
7.在‘{}’内部写具体实现
int
(^myBlock)(int, int) = ^(int
a, int b){
return a +
b;
};
int
(^myBlock1)(int, int) = ^(int
c, int d){
return c +
d;
};
NSInteger
(^Ming)(NSString *) = ^(NSString *p){
return [p
integerValue];
};
//Block与变量
//在Block内部：
//1.全局变量既可以访问，也可以修改
//2.局部变量只可以访问，不可以修改；如果想要修改，需要使用__block修改局部变量
__block int
count = 5;
int
(^sum)(int) = ^(int a){
count =
20; // 修改局部变量
return a *
count;
};
NSLog(@"%d",sum(10));
//使用Block对数组进行排序
NSArray *arr =
[NSArrayarrayWithObjects:@"asf
60",@"ab
54",@"78",nil];
NSComparator sortBlock =
^(id obj1, id obj2){
return
[obj1 compare:obj2];
};
arr = [arr
sortedArrayUsingComparator:sortBlock];
NSLog(@"%@",arr);
//字符串比较排序
[arr
sortedArrayUsingComparator:^NSComparisonResult(id
obj1, id obj2) {
return
[obj1 compare:obj2];
}];
//根据数值排序
NSArray *arr1 =
[NSArrayarrayWithObjects:@"456",@"15",@"97",@"1123",
nil];
NSComparator paixu =
^(id obj1, id obj2){
return
[obj1 compare:obj2];
};
arr1 = [arr1
sortedArrayUsingComparator:^NSComparisonResult(id
obj1, id obj2) {
NSInteger
obj1Int = [obj1 integerValue];
NSInteger
obj2Int = [obj2 integerValue];
if
(obj1Int > obj2Int) {
returnNSOrderedDescending;
}else
if(obj1Int < obj2Int){
return NSOrderedAscending;
}else{
return NSOrderedSame;
}
}];
NSLog(@"%@",arr1);
//创建5个学生对象
Student *stu1 =
[[Studentalloc]initWithName:@"zhang"withAge:12];
Student *stu2 =
[[Studentalloc]initWithName:@"li"withAge:21];
Student *stu3 =
[[Studentalloc]initWithName:@"sun"withAge:18];
Student *stu4 =
[[Studentalloc]initWithName:@"wang"withAge:32];
NSMutableArray
*stu = [NSMutableArrayarray];
[stu
addObject:stu1];
[stu
addObject:stu2];
[stu
addObject:stu3];
[stu
addObject:stu4];
[stu
sortUsingComparator:^NSComparisonResult(id
obj1, id obj2) {
Student
*stu1 = (Student *)obj1;
Student
*stu2 = (Student *)obj2;
if ([stu1
getage] > [stu2 getage]) {
return
NSOrderedDescending;
}if ([stu1
getage] < [stu2 getage]) {
return NSOrderedAscending;
}else{
return NSOrderedSame;
}
}];
for
(Student *student in stu) {
NSLog(@"%@", student);
}
NSLog(@"
");
[stu
sortUsingComparator:^NSComparisonResult(id
obj1, id obj2) {
Student
*stu1 = (Student *)obj1;
Student
*stu2 = (Student *)obj2;
return
[[stu1 getname]compare:[stu2
getname]];
}];
for
(Student *str in stu) {
NSLog(@"%@", str);
}
//字面量的使用
NSString *p =
@"abc";
NSArray *arry
=@[@"A", @"B",
@"C"];
NSArray *a =
a[2];
NSDictionary *dict =
@{@"kkk":
@"ooo",@"kk2":
@"ooo"};
NSLog(@"%@",dict[@"kkk"]);
//dict[@"xxx"]
提取“键”对应的值
@{@"asd":
@"789"};
//设置键、值
block 数值排序 字面量的使用,布布扣,bubuko.com