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    • iOS journey

    This is a collection of ios learning experience and knowleadge, and will be updated in the coming days. 2015.06.17 @ suzhou

    ios framework

    1.core os

    • osx kernel,

    • power management,

    • Mach 3.0,

    • file system

    • …

    2.core services

    • collections,

    • core location

    • networking

    • SQLite

    • threading

    • preference

    • net services

    • (add more later…)

    3.Media

    • core audio

    • jpeg, png, tiff,…

    • openAL

    • openGL ES

    • (add more later…)

    4.cocoa touch

    • multi touch

    • alert

    • core motion

    • web view

    • view hierarchy

    • controls

    • (add more later …)

    MVC

    model view controller

    mvc introduction</img>

    objective c

    @property(strong/weak,nonautomic)

    strong:release memory until all reference pointer set to nil or change to other object. weak: will not retain the object memory , and will be set to nil if no one else has a stong pointer to this object.

    there is an example:

    @property (nonatomic, strong) NSString *string1;   

@property (nonatomic, strong) NSString *string2; 
@synthesize string1;   

@synthesize string2;   
self.string1 = @"String 1";   

self.string2 = self.string1;   

self.string1 = nil;  

NSLog(@"String 2 = %@", self.string2);  

==>output:String 2 = String 1

    but

    @property (nonatomic, strong) NSString *string1; 
    @property (nonatomic, weak) NSString *string2; 
@synthesize string1;   

@synthesize string2;   
self.string1 = @"String 1";   

self.string2 = self.string1;   

self.string1 = nil;  

NSLog(@"String 2 = %@", self.string2);  

==>output:String 2 = nil

    xcode

    Add this phase to list some problem when using xcode as part of ios learning.

    1.

    directory not found for option ‘-L…’

    clang: error: linker command failed with exit code 1 (use -v to see invocation)

    2.

    LLVM:low level virtual machine

    Clang

    llvm 与clang的介绍： https://linuxtoy.org/archives/llvm-and-clang.html

    wiki:

    Apple 使用 LLVM 在不支持全部 OpenGL 特性的 GPU (Intel 低端显卡) 上生成代码 (JIT)，令程序仍然能够正常运行。之后 LLVM 与 GCC 的集成过程引发了一些不快，GCC 系统庞大而笨重，而 Apple 大量使用的 Objective-C 在 GCC 中优先级很低。此外 GCC 作为一个纯粹的编译系统，与 IDE 配合很差。加之许可证方面的要求，Apple 无法使用修改版的 GCC 而闭源。于是 Apple 决定从零开始写 C family 的前端，也就是基于 LLVM 的 Clang 了。